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PubMed2001

Genes of SHR rats protect spontaneously diabetic BB/OK rats from diabetes: lessons from congenic BB.SHR rat strains.

Diabetes in BB rats share many common features with human type 1 diabetes. One of them is the complex and polygenic nature of disease. Analysis of cross hybrids of diabetic BB/OK rats and rats of different diabetes-resistant strains has demonstrated that beside the MHC genes, Iddm1 and the lymphopenia, Iddm2, additional non-MHC genes are involved in diabetes development. To study the importance of the non-MHC genes, Iddm4 and Iddm3, two congenic BB.SHR rat strains were generated by recombining a segment of the SHR chromosome 6 (Iddm4; termed BB.6S; 15cM) or chromosome 18 (Iddm3; termed BB.18S; 24cM) into the BB/OK background by serial backcrossing and marker-aided selection. The characterization of both congenic strains demonstrates a drastic reduction of diabetes frequency in comparison to the BB/OK strain (86% vs 14% and 34%). It is supposed that diabetes protective genes of SHR must be located on both chromosomal segments and that these suppress the action of the essential and most important genes of diabetes development in the BB/OK rat, Iddm1, and Iddm2.

Animals↗

PubMed1984

Spontaneous unstable unc-22 IV mutations in C. elegans var. Bergerac.

This paper describes a mutator system in the nematode Caenorhabditis elegans var. Bergerac for the gene unc-22. Of nine C. elegans and two C. briggsae strains tested only the Bergerac BO strain yielded mutant animals at a high frequency and the unc-22 IV gene is a preferred mutational target. The forward spontaneous mutation frequency at the unc-22 locus in Bergerac BO is about 1 X 10(-4), and most of these spontaneous unc-22 mutations revert at frequencies between 2 X 10(-3) and 2 X 10(-4). Both the forward mutation frequency and the reversion frequency are sensitive to genetic background. Spontaneous unc-22 mutations derived in a Bergerac background and placed in a primarily Bristol background revert at frequencies of less than 10(-6). When reintroduced into a Bergerac/Bristol hybrid background the mutations once again become unstable. The mutator activity could not be localized to a discrete site in the Bergerac genome. Nor did mutator activity require the Bergerac unc-22 gene as a target since the Bristol unc-22 homolog placed in a Bergerac background also showed high mutation frequency. Intragenic mapping of two spontaneous unc-22 alleles, st136 and st137, place both mutations in the central region of the known unc-22 map. However, these mutations probably recombine with one another, suggesting that the unstable mutations can occur in more than one site in unc-22. Examination of the phenotypic effect of these mutations on muscle structure indicates that they are less severe in their effect than a known amber allele. We suggest that this mutator system is polygenic and dispersed over the nematode genome and could represent activity of the transposable element Tc1.

Alleles↗

PubMed2025

Comorbidity alters the genetic relationship between anxiety disorders and major depression.

BACKGROUND: Comorbid anxiety disorders (ANX) and major depression (MD) have worse clinical outcomes than either disorder alone. Analysis of genomic data based on comorbidity status may reveal more precise biological pathways and causal relationships with potential clinical implications. We investigated the genetic relationship between ANX and MD with and without mutual comorbidity. METHODS: We leveraged data from UK Biobank to perform disorder-specific genome-wide association studies (GWAS) of ANX-only (n=189,422) and MD-only (n=194,339) and generate polygenic risk scores (PRS). The Norwegian Mother, Father, and Child Cohort (MoBa, n = 130,992) served to test the associations of PRS with diagnoses. MD and ANX GWAS, including comorbidities (MD-comorbid and ANX-comorbid), were used for comparison. Genetic correlations were compared by comorbidity status, and Mendelian randomization was employed to assess causal relationships. RESULTS: The MD-only PRS showed a stronger association with MD-only compared to ANX-only cases (Z=3.74; Padjusted=0.002); however, MD-comorbid PRS did not show a significant difference (Z=2.71; Padjusted=0.08). The genetic correlation between ANX-only and MD-only was 0.53, lower than between ANX-comorbid and MD-comorbid (0.90). ANX-only showed a causal relationship with MD-only (Padjusted=0.015), but not vice versa, and contrasted the bidirectional causal relationship (Padjusted=2.9e-12, and Padjusted=9.3e-06) when comorbidity was included. Gene sets of MD-comorbid, ANX-comorbid, and MD-only, but not of ANX-only, were enriched for immune regulation pathways such as interleukin production. CONCLUSIONS: ANX and MD show more distinct genetics when comorbid cases are excluded, and ANX may be causal for MD. Disorder-specific genetic studies help uncover more relevant biological mechanisms and guide tailored clinical interventions.

Journal Article↗

PubMed2006

Rheumatoid arthritis, a complex multifactorial disease: on the way toward individualized medicine.

With the availability of the human genome sequence and those of related species like chimpanzee, mouse, and rat, data driven research for tackling the molecular grounds of rheumatoid arthritis (RA), a multifactorial polygenic disease, can be considered a realistic challenge to the scientific community. A comprehensive research strategy is presented enabling the integration of multiple research efforts on studying autoimmunity by so called systems biology approaches. An integrative scientific concept is discussed of how to unravel molecular mechanisms of complex diseases by making use of state-of-the-art methodologies in functional and comparative genomics. A continuous interchange of data-driven and hypothesis-driven research is adjoined to determine the nature of rheumatic diseases with autoimmune background. Instead of studying single genes and proteins, RNA and protein microarray profiles are currently obtained in numerous research projects producing read-outs termed gene signatures rather than DNA and/or protein markers. A comprehensive study of the RNA, protein, and metabolite regimes is undertaken that eventually will lead to a "holistic" view of how all respective molecules, pathways and cells themselves interact with each other. Some of the above mentioned research aspects have already been studied by the authors, hopefully leading to new diagnostics and therapeutics in the future.

Animals↗

PubMed2026

Urban heat island and risk of rheumatoid arthritis: Insights from genetic predisposition and proteomics.

BACKGROUND: Urban heat island (UHI) exposure is an increasingly common consequence of urbanization and climate warming, but its association with rheumatoid arthritis (RA) risk remains unclear. OBJECTIVE: To investigate the association between UHI exposure and incident RA, and to further assess the roles of genetic susceptibility and plasma proteomic profiles in this association. METHODS: This study included 400,628 urban residents with UHI exposure data and free of RA at baseline. Cox proportional hazards models were used to evaluate the association between UHI exposure and incident RA. Polygenic risk scores were used to assess effect modification by genetic susceptibility. Proteomic analyses identified candidate proteins and enriched pathways underlying the association. Mendelian randomization, colocalization, and mediation analyses assessed causal relevance and mediation. RESULTS: Over a median follow-up of 14.05 years, 5397 incident RA cases were documented. Each standard-deviation increase in UHI exposure was associated with a 17% higher risk of RA. This association was more pronounced among older adults and individuals with lower socioeconomic status. An additive interaction was observed between UHI exposure and genetic risk for RA. Proteomic analyses suggested that this association may involve not only canonical immune-inflammatory pathways, but also hypoxia response and protein transport, with CD40, VCAM1, and SUGP1 emerging as potential molecular mediators. CONCLUSIONS: UHI exposure may be a modifiable environmental risk factor for RA and provide new insights into the biological mechanisms underlying this association.

Humans↗

PubMed2002

Genome scanning of the HXB/BXH sets of recombinant inbred strains of the rat for quantitative trait loci associated with conditioned taste aversion.

In the current study, we searched for quantitative trait loci (QTL) responsible for a conditioned taste aversion (CTA) measured as a decrease in the intake of a saccharin conditioned stimulus followed by an i.p. injection of 0.15 M LiCl (lithium chloride) (2 ml/100 g body weight). A genome scanning for QTL associated with CTA was performed in the HXB/BXH sets of recombinant inbred (RI) strains derived from the Brown Norway (BN-Lx) rat and the spontaneously hypertensive rat (SHR). The BN-Lx progenitor showed a significantly stronger CTA (8.3+/-2.8%) than the SHR progenitor (27.8+/-3.3%, p < .0001). The distribution of CTA values among RI strains was continuous, suggesting a polygenic mode of inheritance. Genome scanning of RI strains with more than 700 gene markers revealed a significant association of CTA with the D2Cebr11s4 marker on chromosome 2 (LRS = 22.7) and with the D4Cebrp149s8 marker on chromosome 4 (LRS = 23.4). The chromosome 2 putative QTL was confirmed by detecting a significant difference in CTA between the SHR progenitor (27.8+/-3.3%) and the SHR-2 (SHR.BN-D2Rat171/D2Arb24) congenic strain (13.1+/-4.4%, p < .01) that are genetically identical except for a segment of chromosome 2 that was transferred onto the genetic background of the SHR from the BN strain.

Animals↗

PubMed2026

Meta-ERS: an exposome-based risk score using non-genetic factors to guide osteoporosis prevention.

BACKGROUND: Osteoporosis is influenced by both genetic and environmental factors, yet the relative contribution of the exposome remains unclear. This study aimed to systematically identify non-genetic exposures related to osteoporosis and develop an exposome risk score (ERS) to evaluate individual osteoporosis susceptibility. METHODS: We conducted an exposome-wide analysis of 477,792 UK Biobank participants to identify key exposures associated with osteoporosis. The selected exposures were combined into a weighted Meta-ERS and validated in the Scotland/Wales cohort. The Meta-ERS was further compared with polygenic risk scores (PRS) and linked to plasma proteomics to explore underlying biological pathways. RESULTS: We identified 41 independent non-genetic exposures spanning socioeconomic status, mental health, sleep, diet, smoking, physical activity, environment, and marital status, with socioeconomic status and mental health emerging as the most significant drivers. Based on the identified exposures, we constructed eight domain-specific exposure risk scores and integrated them into a weighted Meta-ERS. The Meta-ERS (R2 = 5.1%; Proportion of Chi-Square = 14.3%) demonstrated an ability to explain osteoporosis variation that was on par with polygenic risk scores (R2 = 4.8%; Proportion of Chi-Square = 12.0%). Importantly, modifying unfavorable exposures mitigated the negative effect of PRS on osteoporosis, particularly among high PRS individuals (1.5- to 1.8-fold greater absolute risk reduction than in those with low PRS). Proteomic analyses further revealed potential mechanisms through which the exposome influences osteoporosis, including hormonal regulation, inflammation, ossification, muscle development, lipid metabolism, and accelerated bone aging. Among these, growth/differentiation factor 15 was identified as a key mediator protein, with a mediation proportion of 13.13%-36.52%. CONCLUSIONS: The Meta-ERS facilitates the quantification of individual osteoporosis risk and identifies modifiable exposures for targeted prevention. Its application can enable personalized risk stratification and guide lifestyle or environmental interventions.

Aged↗

PubMed2004

Mouse models of type 1 and type 2 diabetes derived from the same closed colony: genetic susceptibility shared between two types of diabetes.

Except for rare subtypes of diabetes, both type 1 and type 2 diabetes are multifactorial diseases in which genetic factors consisting of multiple susceptibility genes and environmental factors contribute to the disease development. Due to complex interaction among multiple susceptibility genes and between genetic and environmental factors, genetic analysis of multifactorial diseases is difficult in humans. Inbred animal models, in which the genetic background is homogeneous and environmental factors can be controlled, are therefore valuable in genetic dissection of multifactorial diseases. We are fortunate to have excellent animal models for both type 1 and type 2 diabetes--the nonobese diabetic (NOD) mouse and the Nagoya-Shibata-Yasuda (NSY) mouse, respectively. Congenic mapping of susceptibility genes for type 1 diabetes in the NOD mouse has revealed that susceptibility initially mapped as a single locus often consists of multiple components on the same chromosome, indicating the importance of congenic mapping in defining genes responsible for polygenic diseases. The NSY mouse is an inbred animal model of type 2 diabetes established from Jcl:ICR, from which the NOD mouse was also derived. We have recently mapped three major loci contributing to type 2 diabetes in the NSY mouse. Interestingly, support intervals where type 2 diabetes susceptibility genes were mapped in the NSY mouse overlapped the regions where type 1 diabetes susceptibility genes have been mapped in the NOD mouse. Although additional evidence is needed, it may be possible that some of the genes predisposing to diabetes are derived from a common ancestor contained in the original closed colony, contributing to type 1 diabetes in the NOD mouse and type 2 diabetes in the NSY mouse. Such genes, if they exist, will provide valuable information on etiological pathways common to both forms of diabetes, for the establishment of effective methods for prediction, prevention, and intervention in both type 1 and type 2 diabetes.

Animals↗

PubMed1992

Polygenic influences on the length of oestrous cycles in inbred mice involve MHC alleles.

Genetic influences on female reproductive cycles were analysed in histocompatibility-congenic strains of mice. Oestrous cycles of young, virgin mice of inbred-congenic strains, hybrid crosses (F1), and parental-hybrid backcrosses (F2) were monitored for 3 months. Oestrous cycles were categorized by length (inter-oestrous interval): 4, 5, 6, or 7-14 days. Mice with the following H-2 haplotypes had a greater proportion of 5-day oestrous cycles: H-2b, H-2r, H-2h2, H-2h4, and H-2i5. In contrast, the H-2k and H-2d haplotypes had mostly 4-day oestrous cycles. Influences of H-2 haplotype were seen on two genetic backgrounds, C57BL/10Sn and C3H. Non-H-2 alleles were also implied by different patterns of cycles between strains with the same H-2b haplotype: C57BL/10Sn with predominantly 5-day cycles vs. C57BL/6J with a mix of 4- and 5-day cycles. The genetic basis for strain differences was investigation in F1 hybrids and their backcrosses. F1 hybrids of an H-2b (C57BL/10Sn; 5-day cycles) and an H-2k (B10.BR; 4-day cycles) strain had mostly 5-day cycles, indicating dominance of an H-2b allele(s). However, F1 hybrids from the reciprocal B6 x B10 cross (both H-2b) also display a preponderance of 5-day cycles, indicating dominance of a non-H-2 autosomal allele from the C57BL/10Sn strain. Among F2 mice, a '4-day' phenotype segregated with homozygosity for the k haplotype (P < 0.05, chi 2). These findings demonstrate the influence of genetic differences at the major histocompatibility complex on oestrous cycles.

Alleles↗

PubMed2025

Genomic structural equation modeling elucidates the shared genetic architecture of allergic disorders.

BACKGROUND: The intricate shared genetic architecture underlying allergic disorders-including allergic asthma, atopic dermatitis, contact dermatitis, allergic rhinitis, allergic conjunctivitis, allergic urticaria, anaphylaxis, and eosinophilic esophagitis-remains incompletely characterized. METHODS: Our study employed genomic structural equation modeling (Genomic SEM) to define the common factor representing the shared genetic architecture of allergic disorders. Coupled with diverse post-GWAS analytical methods, we aimed to discover susceptible loci and investigate genetic associations with external traits. Furthermore, we explored enriched genetic pathways, cellular layers, and genomic elements, and investigated putative plasma protein biomarkers. Polygenic risk score (PRS) analyses, leveraging our integrated GWAS data, were conducted to assess chromosomal-level risk associations for allergic disorders. RESULTS: A well-fitted genomic SEM integrated GWAS data, revealing the shared genetic architecture of allergic disorders. We identified a total of 2038 genome-wide significant SNP loci (p < 5e-8), including 31 previously unreported loci. Fine-mapping of variants and gene sets pinpointed 2 causal variants and 31 candidate susceptible genes. Genetic correlation analyses further illuminated the shared genetic architecture underlying multiple traits, notably psychiatric disorders. Preliminary findings identified four putative causal plasma protein biomarkers. CONCLUSION: Notably, this study presents the first comprehensive genetic characterization of allergic disorders through a GWAS analysis of an unmeasured composite phenotype, providing novel insights into shared etiological pathways across these conditions.

Humans↗

PubMed1998

Vitamin D receptor gene start codon polymorphisms (FokI) and bone mineral density: interaction with age, dietary calcium, and 3'-end region polymorphisms.

Osteoporosis is a polygenic disease, whose determining loci have not yet been identified. Vitamin D receptor (VDR) gene polymorphisms in the 3'-end region (as determined by the enzymes BsmI and ApaI) have been inconsistently associated with bone mineral mass. More recently, VDR start codon polymorphisms (as determined by the enzyme FokI) have been found to be related to adult bone mineral density (BMD) in pre- and postmenopausal American women. We investigated the association between BMD and FokI genotypes in premenopausal European-Caucasian women as well as in prepubertal girls from the same genetic background and examined the interaction with VDR 3'-end region polymorphisms and with dietary calcium intake. Areal BMD (g/cm2) was measured by dual-energy X-ray absorptiometry at the level of the lumbar spine, femoral neck, and femoral shaft in 177 healthy premenopausal women (age range, 18.7-56.0 years) as well as in 155 prepubertal girls (age range, 6.6-11.4 years). Genotyping for FokI, BsmI, and ApaI VDR polymorphisms was performed using polymerase chain reaction methods. FokI genotype-dietary calcium interaction was cross-sectionally analyzed in all subjects and longitudinally in 103 prepubertal girls enrolled in a calcium intervention trial. The prevalence of FokI VDR gene polymorphisms in this cohort was 15% for ff, 50% for Ff, and 35% for FF. In the whole cohort of premenopausal women or prepubertal girls, no significant association was found between FokI VDR gene polymorphisms and BMD, even adjusted for age (Z score), weight, height, and calcium intake. Further analysis of FokI VDR gene polymorphisms and dietary calcium intake suggested a possible interaction in BMD determination, since a trend for an association with FokI genotypes was more evident at high than low calcium intake in both cross-sectional and longitudinal studies. Furthermore, cross-genotyping FokI and either BsmI or ApaI VDR polymorphisms suggested that the ff genotype was associated with a significantly lower lumbar spine BMD in bb and aa prepubertal girls. FokI VDR gene polymorphisms were not significantly associated with BMD in healthy European-Caucasian females. However, cross-genotyping of the VDR 3'-end and start codon polymorphic regions may provide a further insight into the complex determination of BMD.

Absorptiometry, Photon↗

PubMed2026

Shared genetic basis and spatial cellular atlas of psoriasis and metabolic syndrome.

BACKGROUND: Psoriasis (PS) and metabolic syndrome (MetS) frequently co-occur. Characterizing their shared genetic architecture and spatially enriched cellular populations may clarify the context of their co-occurrence and generate hypotheses for functional validation. METHODS: We integrated genome-wide association study (GWAS) summary statistics for PS, MetS, and five related components with spatially resolved single-cell transcriptomic data. Global and local genetic correlations were assessed using linkage disequilibrium score regression, genetic covariance analysis, high-definition likelihood, and local analysis of variant association. A bivariate causal mixture model quantified polygenic overlap. Conditional/conjunctional false discovery rate and composite-null pleiotropy analyses identified shared susceptibility loci. Finally, gsMap evaluated trait-associated enrichment across annotated embryonic tissues at single-cell resolution. RESULTS: Genetic approaches identified significant genome-wide correlations and polygenic sharing between PS, MetS, and its components. Local and cross-trait analyses identified region-specific signals and cross-validated shared loci. gsMap revealed trait-specific tissue enrichment. PS showed the strongest enrichment in the epidermis (pCauchy = 1.0573 × 10  - ⁴), adipose tissue (pCauchy = 1.5366 × 10 - ⁴), and liver (pCauchy = 1.0167 × 10 - ³). Across MetS, FBG, HDL-C, hypertension, and TG, enriched regions mainly involved the liver, adipose tissue, and epidermis. WC enrichment was predominantly observed in adipose tissue (pCauchy = 1.7823 × 10 - ⁴), with no significant liver or epidermal enrichment. CONCLUSION: Integrating GWAS with single-cell transcriptomic and spatial information characterized shared genetic architecture between PS and MetS-related phenotypes and their spatial enrichment patterns. These findings provide a framework for generating testable hypotheses about comorbidity biology and guiding future functional and clinical validation.

Psoriasis↗

PubMed2026

Refining the Genetic Contribution to Type 2 Diabetes Subtypes.

BACKGROUND: Type 2 diabetes (T2D) is a complex and highly heterogeneous disease driven in part by genetic predisposition and can be stratified into clinical subgroups to aid disease management. We recently grouped T2D subjects in the Qatar Biobank (QBB) cohort into Severe Insulin-Deficient Diabetes (SIDD), Severe Insulin-Resistant Diabetes (SIRD), Mild Obesity-Related Diabetes (MOD) and Mild Age-Related Diabetes (MARD) subtypes. Herein, we focused on the genetic makeup of these subtypes. METHODS: We used the QBB cohort (n = 13,808), of whom 2687 were with T2D, and comprehensively assessed polygenic risk scores (PGS) across T2D subtypes, investigated genetic loci associated with each subtype by leveraging the most recent and largest GWAS for T2D, evaluated SNP associations across T2D genetic clusters, and identified protein interaction pathways associated with these distinct T2D subtypes. RESULTS: MOD showed consistently lower PGS compared with other T2D subtypes across all tested scores. SIDD showed more associations with SNPs mapping to residual glycemic cluster compared with other T2D subtypes. The incremental analysis of PGS004838 demonstrated a high ΔAUC of 0.101 for SIDD and a moderate ΔAUC of 0.068 for SIRD, but not for MOD and MARD. Protein interaction analyses identified candidate subtype-associated gene networks linked to pathways related to glucose homeostasis in SIDD, insulin signalling and hepatic metabolism in SIRD, body fat distribution in MOD and vascular-related processes in MARD. CONCLUSION: We found heterogeneous genetic architectures across clinically defined T2D subtypes in a Middle Eastern population. Our findings provide evidence supporting differential polygenic burden, subtype genetic associations and subtype-associated biological pathways across T2D subtypes. These observations support the utility of subtype-based genetic analyses for improving biological understanding of T2D heterogeneity.

Humans↗

PubMed2006

Complex genetic architecture revealed by analysis of high-density lipoprotein cholesterol in chromosome substitution strains and F2 crosses.

Intercrosses between inbred lines provide a traditional approach to analysis of polygenic inheritance in model organisms. Chromosome substitution strains (CSSs) have been developed as an alternative to accelerate the pace of gene identification in quantitative trait mapping. We compared a classical intercross and three CSS intercrosses to examine the genetic architecture underlying plasma high-density lipoprotein cholesterol (HDL) levels in the C57BL/6J (B) and A/J (A) mouse strains. The B x A intercross revealed significant quantitative trait loci (QTL) for HDL on chromosomes 1, 4, 8, 15, 17, 18, and 19. A CSS survey revealed that many have significantly different HDL levels compared to the background strain B, including chromosomes with no significant QTL in the intercross and, in some cases (CSS-1, CSS-17), effects that are opposite to those observed in the B x A intercross population. Intercrosses between B and three CSSs (CSS-3, CSS-11, and CSS-8) revealed significant QTL but with some unexpected differences from the B x A intercross. Our inability to predict the results of CSS intercrosses suggests that additional complexity will be revealed by further crosses and that the CSS mapping strategy should be viewed as a complement to, rather than a replacement for, classical intercross mapping.

Animals↗

PubMed2003

High-resolution genetic map of X-linked juvenile-type granulosa cell tumor susceptibility genes in mouse.

SWR/Bm (SWR) female mice spontaneously develop early-onset ovarian granulosa cell (GC) tumors that can progress to metastatic carcinoma and thus provide a model system for human, juvenile-type GC tumors. In SWR mice, GC tumor susceptibility is an inherited, polygenic trait that appears at a low frequency. A dramatic increase in tumor frequency occurs when the autosomal SWR genetic complement is combined with the X-linked Gct4 allele of the mouse strain SJL/Bm (SJL). The modifier effect of the SJL Gct4 allele (Gct4(J)) also shows a strong parent-of-origin effect, occurring only when the Gct4(J) allele is paternally inherited. To genetically localize Gct4, we generated seven congenic mouse strains (SWR.SJL-X1 through -X7) that contained a defined segment of the SJL X chromosome (Chr) on the SWR autosomal strain background and mapped Gct4 to a 3 cM region. To better define the location of Gct4, we created an additional congenic strain (SWR.CAST-X) that contains most of the genetically polymorphic Chr X from the strain CAST/Ei. From crosses of the SWR.CAST-X and SWR.SJL-X congenic strains, we derived males carrying unique combinations of SJL-X and CAST-X segments. Progeny testing subsequently revealed a second SJL-derived, GC tumor frequency modifier gene, Gct6, located 6.5 cM distal to Gct4 on Chr X. In summary, we have mapped two modifier genes on the mouse Chr X that cause high-frequency, juvenile-type GC tumor development in female mice. The identity of these genes will provide a solid foundation for determination of tumor susceptibility genes in human cases of juvenile-type GC tumors.

Animals↗

PubMed2026

The reporting and handling of missing data in genetic epidemiological studies of mental health in childhood and adolescence: A systematic review.

BACKGROUND: Genetic epidemiological analyses of child and adolescent mental health often use data from prospective longitudinal cohorts. Missingness due to selective attrition is therefore an important potential source of bias in such analyses. Informatively reporting on missingness and taking appropriate steps to handle it in analyses can mitigate this potential bias. Here, we aim to systematically assess how researchers report and address missingness in genetic epidemiological studies of child and adolescent mental health-related outcomes using cohort data. METHODS: We systematically searched the Ovid Medline database for studies published between August 2012 and August 2025, reporting polygenic score, genome-wide association, or Mendelian randomization analyses, of data on children or adolescents participating in cohort studies. We extracted information from eligible studies based on criteria adapted from the strengthening and reporting of observational studies in epidemiology (STROBE) guidelines. RESULTS: A total of 133 eligible studies were included, of which 125 (93.98%) reported the number of complete cases in all waves, while 84 (63.16%) detailed the amount of missingness on all key variables. Most studies used complete case analysis, while 39 studies explicitly reported applying other methods to handle missingness, with multiple imputation (n = 20, 15.04%) being the most common, followed by full information maximum likelihood 10 (8.1%). Only 18 studies (13.53%) reported an assumed missing mechanism along with the method used to address missingness. Full reporting of both the extent and handling of missingness at the item level was rare, occurring in only 5 (3.76%) and 15 (11.28%) studies, respectively, among the 123 studies that used multi-item instruments. CONCLUSION: Best practice recommendations for reporting on missing data handling emphasize the importance of detailing the proportion of missingness, types of mechanisms underpinning missingness, and details of approaches used. Based on this review, these recommendations for proper reporting of missing data are rarely followed in full.

children and adolescents↗

PubMed1989

Genetic studies on ossification of the posterior longitudinal ligament of the spine.

To study the genetic background in ossification of the posterior longitudinal ligament of the spine (OPLL), 1,030 relatives of probands with cervical OPLL in 347 families were investigated by observing their spinal x-ray films, and the following results were obtained. Ossification of the posterior longitudinal ligament was found in 26.15% of the parents of the probands and 28.89% of the siblings of the probands. These prevalences were significantly higher than in the general population. The segregation rate in the siblings corresponded neither with the hypothesis of autosomal dominant inheritance nor with that of autosomal recessive inheritance. The possibility of polygene inheritance was also ruled out, considering the risk of recurrence in the siblings of the probands. However, owing to the segregation rate in the siblings exceeding 0.25 and the high prevalence of OPLL in the parents, OPLL was suggested to be a disorder possibly controlled by autosomal dominant inheritance.

Adult↗

PubMed2005

Construction and characterization of a genomic BAC library for the Mus m. musculus mouse subspecies (PWD/Ph inbred strain).

BACKGROUND: The genome of classical laboratory strains of mice is an artificial mosaic of genomes originated from several mouse subspecies with predominant representation (>90%) of the Mus m. domesticus component. Mice of another subspecies, East European/Asian Mus m. musculus, can interbreed with the classical laboratory strains to generate hybrids with unprecedented phenotypic and genotypic variations. To study these variations in depth we prepared the first genomic large insert BAC library from an inbred strain derived purely from the Mus m. musculus-subspecies. The library will be used to seek and characterize genomic sequences controlling specific monogenic and polygenic complex traits, including modifiers of dominant and recessive mutations. RESULTS: A representative mouse genomic BAC library was derived from a female mouse of the PWD/Ph inbred strain of Mus m. musculus subspecies. The library consists of 144,768 primary clones from which 97% contain an insert of 120 kb average size. The library represents an equivalent of 6.7 x mouse haploid genome, as estimated from the total number of clones carrying genomic DNA inserts and from the average insert size. The clones were arrayed in duplicates onto eight high-density membranes that were screened with seven single-copy gene probes. The individual probes identified four to eleven positive clones, corresponding to 6.9-fold coverage of the mouse genome. Eighty-seven BAC-ends of PWD/Ph clones were sequenced, edited, and aligned with mouse C57BL/6J (B6) genome. Seventy-three BAC-ends displayed unique hits on B6 genome and their alignment revealed 0.92 single nucleotide polymorphisms (SNPs) per 100 bp. Insertions and deletions represented 0.3% of the BAC end sequences. CONCLUSION: Analysis of the novel genomic library for the PWD/Ph inbred strain demonstrated coverage of almost seven mouse genome equivalents and a capability to recover clones for specific regions of PWD/Ph genome. The single nucleotide polymorphism between the strains PWD/Ph and C57BL/6J was 0.92/100 bp, a value significantly higher than between classical laboratory strains. The library will serve as a resource for dissecting the phenotypic and genotypic variations between mice of the Mus m. musculus subspecies and classical laboratory mouse strains.

Animals↗