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PubMed1989

Genetic analysis of IDDM: summary of GAW5 IDDM results.

This paper summarizes the analyses by participants in the insulin-dependent diabetes mellitus (IDDM) component of Genetic Analysis Workshop 5 (GAW5). The data were obtained from 94 families with two or more IDDM sibs. Topics treated in the Workshop analysis included the following: methods for detecting associations and linkage, the contribution by HLA-linked and -unlinked loci to IDDM susceptibility, the role of subtypes of the serologically defined HLA specificities, the implications of associated diseases other than IDDM in the families, the significance of antibodies to Coxsackie viruses, and of autoantibodies to pancreatic islet cells and insulin, and the use of genetic models to analyze the inheritance of IDDM. There was agreement that an explanation for the data on multiplex IDDM families must include the following features: 1) There is a susceptibility locus (or loci) in the HLA region. 2) The HLA-linked factor(s) are more complex than a single locus with one disease and one nondisease allele. 3) There is additional familial correlation beyond that explained by HLA-linked susceptibility, which may be genetic and/or environmental. With regard to the third feature, IDDM-GAW5 included data on variation in Gm haplotypes and at the insulin gene, two regions unlinked to HLA. However, there was no direct evidence (i.e., from marker segregation) that the additional factor, if genetic, is linked to either Gm or the insulin gene. Nevertheless, a significant difference was found between "diabetic" and "control" insulin genes with respect to frequency of class 1 alleles for the 5' flanking polymorphism, strongly suggesting linkage.

Data Collection↗
PubMed1993

Genetic analysis of the maternal factors controlling the survival of trisomy 16 mouse fetuses.

The B x H recombinant inbred strains of mice were used to undertake a genetic analysis of the maternal factors controlling the survival of trisomy 16 fetuses. The data presented indicate that the prevalence of trisomic fetuses on day 15 of gestation varies significantly with the genetic background of the mother. The strain difference in the frequency of trisomy appears to be the result of selective elimination of trisomic fetuses. Various statistical methods employed to elucidate the genetic architecture of the trait from the recombinant inbred strains data indicate that the number of loci involved in the selection process ranges from one to five. Linkage association with two loci has been found; however, with a low probability level (P = 0.292).

Animals↗
PubMed1995

Quantitative genetic analysis of injury liability in infants and toddlers.

A threshold model of latent liability was applied to infant and toddler twin data on total count of injuries sustained during the interval from birth to 36 months of age. A quantitative genetic analysis of estimated twin correlations in injury liability indicated strong genetic dominance effects, but no additive genetic variance was detected. Because interpretations involving overdominance have little research support, the results may be due to low order epistasis or other interaction effects. Boys had more injuries than girls, but this effect was found only for groups whose parents were prompted and questioned in detail about their children's injuries. Activity and impulsivity are two behavioral predictors of childhood injury, and the results are discussed in relation to animal research on infant and adult activity levels, and impulsivity in adult humans. Genetic epidemiological approaches to childhood injury should aid in targeting higher risk children for preventive intervention.

Adult↗
PubMed1977

Genetic analysis of Escherichia coli O111:B4, a strain of medical and biochemical interest.

Procedures have been worked out which allow, for the first time, the genetic analysis of Escherichia coli O111:K58:H2 (O111:B4). The approximate map position of mutant loci was determined by mating with 15 Hfr strains of E. coli K-12. In addition, P1 transduction procedures were used for establishing relative gene order and linkage for any region of the E. coli O111:B4 chromosome. To obtain these, it was necessary to select for a rare P1 lysogen since E. coli O111:B4 is resistant to phage P1. Finally, genetic homology between E. coli strains K-12 and O111:B4 is suggested since they can form stable haploid hybrids, and several loci have similar map positions in the two strains.

Chromosome Mapping↗
PubMed1997

Quantitative genetic analysis of susceptibility to hookworm infection in a population from rural Zimbabwe.

Overdispersion is a common feature of population distribution patterns for hookworm infection in humans. Genetic factors may be partially responsible for this observed increased susceptibility in a fraction of the exposed population. However, the hypothesis that there are genetic components to susceptibility to this infectious disease has not been tested explicitly. The purpose of this study is to quantify the influence of genetic factors on patterns of hookworm infection in a rural population in Zimbabwe. A quantitative measure of hookworm load, number of hookworm eggs per gram of feces, as determined by the Kato thick smear technique, was available for 289 individuals. Of these, 279 individuals were members of 62 nuclear families and 10 were independent individuals. We analyzed the hookworm data in combination with the pedigree structure of the sampled individuals using quantitative genetic analysis techniques. Using this variance decomposition approach, we estimated the heritability of hook worm load to be 0.37 +/- 0.09 (p < 0.0001). This significant heritability indicates that 37% of the variation (after correcting for the effects of covariates) in hookworm eggs per gram observed in this population is attributable to genetic factors. The results suggest that further investigation and characterization of the genetic components influencing susceptibility to hookworm infection are warranted.

Adolescent↗
PubMed1995

Genetic analysis of Japanese patients with myophosphorylase deficiency (McArdle's disease): single-codon deletion in exon 17 is the predominant mutation.

We report molecular genetic analysis of 11 Japanese patients with myophosphorylase deficiency (McArdle's disease). Four reported mutations, frequently observed in patients with McArdle's disease, in exons 1, 5, 14 and 17 were investigated. Seven patients out of 11 were homozygous for a single-codon deletion at codon 708/709 in exon 17 and one patient was heterozygous for a single-codon deletion with an unknown mutant allele. In contrast, the predominant mutation reported in US and UK patients (CGA to TGA at codon 49 in exon 1), accounting for 75% and 83% of the cases, respectively, was not found in any of the Japanese patients. Results suggest that the predominant mutation in Japanese patients is a single-codon deletion at codon 708/709 in exon 17 (found in 73% of our patients) and differs from the most common mutation in US or UK patients.

Adolescent↗
PubMed2000

Genetic analysis of deciduous tooth size in Australian twins.

Investigations of permanent dental crown size in twins and family groups indicate a high degree of transmissible control, but little is known about the relative contributions of genetic and environmental factors to variation in size of the deciduous (primary) teeth. Here, maximum mesiodistal and buccolingual crown dimensions of maxillary and mandibular primary teeth were measured from dental models of 602 individuals, including 99 monozygous (MZ) twin pairs, 81 dizygous (DZ) same-sex pairs, 41 DZ opposite-sex pairs, and 160 singletons. Data were subjected to univariate genetic analysis with the structural-equation-modelling package, Mx using the normal assumptions of the twin model. A model incorporating additive genetic (A) and unique environmental (E) variation was found to be the most parsimonious for all tooth-size variables. Estimates of heritability for deciduous crown size ranged from 0.62 to 0.91. This study shows that variation in deciduous crown size has a strong genetic component, similar to that observed in the permanent dentition. Further studies are required to determine whether the underlying genetic mechanisms are the same for both deciduous and permanent teeth.

Analysis of Variance↗
PubMed2000

Prenatal diagnosis and genetic analysis of double trisomy 48,XXX,+18.

Prenatal diagnosis of simultaneous occurrence of double trisomy involving chromosomes 18 and X is extremely rare. We report on the prenatal diagnosis, genetic analysis and clinical manifestations of a fetus with both trisomy 18 and trisomy X. A 26-year-old, para 1 woman was referred for genetic counselling at 36 weeks' gestation with the sonographic findings of intrauterine growth retardation (IUGR), polyhydramnios, ventricular septal defect, and an enlarged cisterna magna. Both cordocentesis and amniocentesis revealed a consistent karyotype of 48,XXX,+18. Quantitative fluorescent polymerase chain reaction using polymorphic small tandem repeat markers specific for chromosomes 18 and X rapidly determined that both aneuploidies arose as a result of non-disjunction in maternal meiosis II. Our case shows that two non-disjunction events can occur not only in the same parent, but also in the same cell division. Our case also shows that double trisomy, 48,XXX,+18, can demonstrate an enlarged cisterna magna, IUGR and polyhydramnios in prenatal ultrasound.

Adult↗
PubMed2003

[Genetic analysis of the duration of the vegetative period in cotton Gossypium hirsutum L. with background of various nitrogen level in soil].

Using Hayman's model of genetic analysis of the F1 hybrids from crosses between early- and late-ripening forms of cotton Gossypium hirsutum L., we examined inheritance of the duration of vegetative period at various contents of nitrogen in soil. Two variants of hybrid plants were studied. With the natural content of soil nitrogen, incomplete directionally dominance of earliness over late ripening with prevalence of additive gene effect of nonallelic interactions was observed. The genetic formulas of this trait proved to change with varying nitrogen nutrition.

Gossypium↗
PubMed2003

Prenatal diagnosis of spinal muscular atrophy by genetic analysis of circulating fetal cells.

Spinal muscular atrophy (SMA) has a prevalence of one in 6000 births and a one in 40 heterozygote frequency. We aimed to develop a routine test for non-invasive prenatal diagnosis. We tested blood with ISET (isolation by size of epithelial tumour or trophoblastic cells) in 12 pregnant women whose babies were at risk of SMA. Using genetic analysis of fetal cells, we identified SMA in all nine isolated from the three mothers carrying an affected child. There was no mutation in any of the 26 fetal cells isolated from the nine women with an unaffected child. Our results show that non-invasive detection of genetic diseases by the analysis of maternal blood is feasible.

Female↗
PubMed1998

[Application of modified comparative genomic hybridization in the genetic analysis of 5 lymphoid neoplasms].

To analyze the utility of performing modified comparative genomic hybridization (mCGH) as a complementary technique to conventional cytogenetic techniques in the genetic analysis of lymphoid neoplasms. Modified comparative genomic hybridization and subsequent FISH techniques were performed in 5 lymphoid neoplasms cases diagnosed in Fundación Jiménez Díaz. The latter was done in order to confirm the results obtained with mCGH. Gains of chromosomal regions not detected with conventional cytogenetic techniques were detected by mCGH. A good correlation in the results obtained between conventional cytogenetic and mCGH techniques was observed. Nevertheless, mCGH enables the detection and subsequent identification of gains of genetic sequences undetectable with cytogenetic techniques with possible diagnostic and prognostic value.

Chromosomes, Human, Pair 10↗
PubMed1979

[Clinical, pathologica and genetic analysis of 53 cases of broncho-pulmonary cancer, still surviving after 5 years (author's transl)].

The authors take up again the clinical, pathological and genetic analysis of 53 bronchial cancers with a survival exceeding 5 years. The operation samples were reexamined; a H.L.A. grouping was done in every cases. On the whole, it concerned patients under 60 in good general condition; the extension of their lesions only required a limited exeresis (lobectomy). The epidermoid form predominates, the lymph node invasion is rare. Seventy four per cent of the patients carry at least one of the following antigens: W 19, A 10, B 5, BW 35. But the study did not prove the existence of a genetic factor conditioning the survival.

Bronchial Neoplasms↗
PubMed1993

Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and diabetes mellitus: molecular genetic analysis and family study.

Two MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) patients with diabetes mellitus (DM), and their family members are described clinically and genetically. The probands have the following features in common; normal early development, short stature, deterioration of intellectual ability, convulsions, cardiac conduction defect, sensorineural hearing loss, cortical blindness, and hemiparesis. Biochemical tests showed high levels of lactate and pyruvate in the blood and cerebrospinal fluid. Muscle biopsy showed ragged-red fibers. Molecular genetic analysis of both patients revealed that they had an A-to-G substitution at nucleotide position 3243 of the mitochondrial DNA in a heteroplasmic fashion. From these clinical and molecular genetic data they were diagnosed as having MELAS. In addition, fasting blood glucose levels were also high and they were diagnosed as having insulin-dependent DM. Some of the maternal family members in both cases also had insulin-dependent DM and several clinical symptoms of MELAS. DM and clinical features of MELAS were transmitted exclusively in the maternal line. In these cases, DM and MELAS might be a clinical manifestation of the same metabolic defect.

Adolescent↗
PubMed1989

Molecular genetic analysis of vaccinia virus DNA polymerase mutants.

To further our understanding of the structure and function of the vaccinia virus DNA polymerase, we have performed fine genetic analysis of three mutants with lesions in the polymerase gene. By performing marker rescue analysis with DNA fragments of decreasing size, each lesion was localized to within 500 base pairs of DNA. The relevant regions of the mutant alleles were then cloned and subjected to DNA sequence analysis, which allowed the assignment of a single nucleotide and amino acid change to each mutant. As well as providing structure-function correlations germane to an understanding of polymerase activity, these data have provided insights into the frequency and possible mechanisms of viral homologous recombination.

Amino Acid Sequence↗
PubMed1990

Biometric genetic analysis of blood pressure in the spontaneously hypertensive rat.

The spontaneously hypertensive rat is the most widely studied animal model of essential hypertension, yet the genetics of transmission of high blood pressure in this strain have not been clearly defined. It has been proposed that in the spontaneously hypertensive rat, blood pressure follows a simple additive mode of inheritance and that the hypertension is primarily determined by a single major locus. To investigate the genetics of transmission of increased blood pressure in the spontaneously hypertensive rat, we performed a biometric genetic analysis of multiple, direct measurements of arterial pressure in unanesthetized, unrestrained rats derived by crossing spontaneously hypertensive rats with two different inbred normotensive strains, the Charles River Wistar-Kyoto rat and the Lewis rat. In both crosses, approximately 60% of the variation in blood pressure could be assigned to genotypic variation. The data fit an additive-dominance model of inheritance in which alleles decreasing blood pressure were partially dominant. Thus, in offspring derived from crosses between spontaneously hypertensive rats and Wistar-Kyoto rats or spontaneously hypertensive rats and Lewis rats that are raised under ordinary laboratory conditions, increased blood pressure is not determined by simple additive effects of alleles at a single major locus. The current findings are consistent with the possibility that in the spontaneously hypertensive rat, hypertension may arise from mutations in alleles that ordinarily act in a dominant fashion to suppress blood pressure.

Animals↗
PubMed2000

Quantitative genetic analysis of circulating levels of biochemical markers of bone formation.

Carboxyterminal propeptide of type 1 collagen (PICP) and bone Gla-protein-osteocalcin (BGP) are the most important components of the organic bone matrix and play a key role in bone formation. To investigate whether and to what extent variation of the plasma levels of these indices of bone turnover depends on genetic factors, we studied 355 adults belonging to nuclear pedigrees. Genetic analysis was carried out in 2 steps: 1) variance decomposition analysis was performed using the FISHER statistical package; and 2) complex segregation analysis implemented in the program package MAN. The effect of age and gender differences, gender hormones, as well as PTH and vitamin-D (calcidiol) plasma levels were evaluated simultaneously with the parameters of variance analysis. The results showed that about 50% of PICP variation is attributable to genetic factors. The effect of age was significant among men and postmenopausal women, whereas calcidiol influenced variation of PICP in premenopausal women. The results of variance analysis showed that some 40% of BGP, adjusted for confounding variables, can be explained in genetic factors. Age and PTH were important covariates for osteocalcin in men and premenopausal women. Exploration of the maximum likelihood estimates of the various hypotheses concerning the mode of intergenerational transmission of PICP and BGP demonstrated a good correspondence to the Mendelian mode of inheritance (i.e., major gene effect).

Adolescent↗
PubMed2007

Tools for the genetic analysis of Mycoplasma.

The mycoplasmas have attracted much scientific attention since they contain the smallest known genomes of any independently viable bacterial species. However, the detailed genetic analysis of these bacteria has lagged behind the well-analyzed bacterial model organisms for a long time. This is due to the use of the UGA codon for tryptophan rather than as stop codon, which had often prevented the expression of full-length Mycoplasma proteins in heterologous hosts. Additionally, insufficient efficiency of homologous recombination prevented the targeted disruption of genes in some species such as M. pneumoniae whereas homologous recombination is operative in other mycoplasmas. Only recently, efficient screening systems for the use of transposon-based mutagenesis have been developed to circumvent this problem and to allow the targeted isolation of desired transposon insertion mutants. With the availability of several Mycoplasma genome sequences, artificial plasmids based on the chromosomal origin of replication were constructed that can now be used for complementation studies and for the stable introduction of foreign genetic material. In this review, we give an overview on recent developments in Mycoplasma genetics that facilitate the genetic manipulation of these interesting organisms.

Codon↗
PubMed1982

Genetic analysis of Candida albicans: identification of different isoleucine-valine, methionine, and arginine alleles by complementation.

By using the spheroplast fusion technique as a tool for genetic analysis, we have demonstrated complementation among three of four isoleucine-valine mutants, two of three methionine mutants, and two arginine mutants of independent origin from two different Candida albicans isolates. The two adenine mutants derived from the same parent strain did not complement. Complementation resulted predominantly from heterokaryon formation and, in some cases, from heterozygote formation. In either case, most fusion products were unstable and showed nuclear as well as chromosomal segregation, in a few cases resulting in recombination of parental auxotrophic markers. However, some fusion products were fairly stable.

Adenine↗