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Identification of carriers of mutant prealbumin gene associated with familial amyloidotic polyneuropathy type I by Southern blot procedures: study of six pedigrees in the Arao district of Japan.

Fifty-six Japanese individuals from six pedigrees with familial amyloidotic polyneuropathy (FAP), together with 2 individuals with symptomatic FAP from an unknown pedigree were analyzed, using the Southern blot procedures for the prealbumin gene structure. A human prealbumin cDNA was used as the probe. Altogether, these individuals included 20 with symptomatic FAP, 30 who were asymptomatic, and 8 disease-free spouses. Twenty individuals with symptomatic FAP were all heterozygous for the prealbumin genes, carrying one normal and one mutant gene. We confirmed the direct linkage between the mutant prealbumin gene and the Japanese type of FAP. Moreover, 10 of the 30 asymptomatic individuals from pedigrees with FAP were also heterozygous for the prealbumin gene. The number of asymptomatic individuals with the mutant prealbumin gene showed age-related decreases, and none was over 40 years. A linkage between the mutant prealbumin gene and serum levels of the prealbumin variant was also evident.

Adolescent↗

Mapping of the Emery-Dreifuss gene through reconstruction of crossover points in two Italian pedigrees.

Two unrelated pedigrees, which show recurrence of Emery-Dreifuss muscular dystrophy (EDMD) in three generations, have been studied using 13 X-linked DNA polymorphisms and somatic cell hybrids to establish the phase of the corresponding alleles in some obligate carriers. The reconstruction of cross-over points on the X chromosomes carrying the EDMD gene excludes from mapping most regions of the X chromosome except for the terminal portion of Xq. Pooled linkage data from the two pedigrees confirm the linkage previously reported with locus DXS15. A cross-over in a carrier female suggests that the EDMD gene is probably located distally to DXS15. In addition the recombinant meioses from one of the two pedigrees suggest the following order for some Xq polymorphic loci: DXS1 (DXYS1-DXS178) DXS42 (F9-DXS15).

Chromosome Mapping↗

Likelihood-based analyses of longitudinal twin and family data: experiences with pedigree-based approaches.

Substantial progress has been made recently in analyses of longitudinal twin and family data, principally for two reasons. The first is the continuing development of more refined models for describing longitudinal data; the second is the widespread availability of analytic methods (e.g. LISREL) with which to implement these models. Computational restrictions have limited likelihood-based analyses of longitudinal genetic data to analyses of covariance matrices or mean squares; however, advances in computer technology now make it feasible to conduct likelihood analyses of longitudinal pedigree data. We consider potential advantages of using pedigree-based methods. Our initial experiences with the application of these methods to simulated twin data, using the FISHER (Lange, K.L., et al., Genet. Epidemiol. 5:471, 1988) quantitative genetics package, are discussed, with particular attention to practical details such as running times on several computers. Preliminary results of the pedigree-based analyses, including robust estimation methods, convincingly demonstrate the failure of methods assuming the multivariate normal distribution for simulated twin data provided by Carey (this issue).

Adolescent↗

Towards the genetic basis of periodic catatonia: pedigree sample for genome scan I and II.

In a genome-wide linkage study, we mapped two major susceptibility loci for periodic catatonia, a phenotype with qualitative disturbances of the psychomotor sphere and a morbidity risk of 26.9% in first-degree relatives of index cases, to chromosome 15q15, and to chromosome 22q13 using nonparametric as well as parametric (autosomal dominant model) analyses. The study included 12 multiplex pedigrees with 135 individuals, among them 57 affected persons. A second genome scan is in progress investigating four families with 21 affected individuals, aiming to confirm linkage results. Age at onset patterns as well as the clinical outcome were similar among affected individuals in both sets of families. Within the pedigrees we observed no physical diseases segregating with periodic catatonia. Under the assumption of genetic homogeneity, the statistical power to detect LOD scores > or = 2.0 was 98.5% in the first set of families, and 57.9% in the second set. Thus, the panel of multiplex pedigrees segregating periodic catatonia seems to represent a homogenous clinical sample, and possesses sufficient statistical power to delineate and confirm linkage to major genetic loci for periodic catatonia.

Adult↗

Microsatellite analysis of wheat chromosome 2D allows the reconstruction of chromosomal inheritance in pedigrees of breeding programmes.

The dwarfing gene Rht8 and the photoperiodic insensitivity gene Ppd-D1 are linked on the short arm of chromosome 2D of bread wheat and play an important role in determining the geographic adaptation of modern wheat varieties. The genes are believed to originate from the old Japanese variety 'Akakomugi' and have been distributed throughout the world by diverse breeding programmes. Twelve microsatellite loci previously mapped on wheat chromosome 2D were used for a retrospective analysis of 59 wheat varieties with known pedigree, to trace the transmittance of the chromosomal region around these genes during extended breeding programmes. Within the range of the screened varieties 100 alleles were detected at the 12 microsatellite loci. For each microsatellite locus, a screen over varieties was performed to find the alleles corresponding to the parental variety 'Akakomugi'. A comparison of wheat varieties carrying the 192-bp allele, at locus Xgwm261-2D which is diagnostic for the presence of the gene Rht8, with the varieties without Rht8, showed linkage disequilibrium of 'Akakomugi' alleles for a segment of chromosome 2D which comprised at least 28 cM. Selection was accompanied with a linkage drag of 'Akakomugi' alleles in the neighbouring loci to Rht8. A diminution of the segment of chromosome 2D originating from 'Akakomugi' during several pedigree generations was observed. Varieties of the early generations were found to carry the whole short arm of chromosome 2D of 'Akakomugi', while the varieties of further selections possessed smaller segments including the diagnostic allele at locus Xgwm261-2D. Our results demonstrate that microsatellites can be successfully used for studying the inheritance of chromosomes within pedigrees of breeding programmes.

Chromosome Mapping↗

Inheritance of microsatellite alleles in pedigrees of Latvian barley varieties and related European ancestors.

Genetic diversity and inheritance of 65 microsatellite (SSR) loci were studied in a set of 37 barley varieties involved in the pedigrees of seven Latvian barley varieties: Abava, Agra, Balga, Imula, Linga, Priekulu 1 and Stendes. Cluster analysis divided all the varieties into two large groups according to their geographic distribution. Moravian, Swedish and Danish varieties clustered separately from varieties from Norway and Finland. The pattern of subgroups of both European and Latvian varieties was in accordance with their pedigree information. Graphical genotypes of microsatellite alleles of all seven barley chromosomes were determined for all the 37 varieties studied. Parental inheritance and transmission of microsatellite alleles through the generations of the pedigrees were analysed. The results confirmed the importance and informative value of microsatellite markers for genetic studies in barley and their utility for barley breeding and other applications in fundamental and applied barley genetics.

Alleles↗

Genetic variance and breeding values for resistance to a wind-borne disease [Sphaerotheca macularis (Wallr. ex Fr.)] in strawberry (Fragaria x ananassa Duch.) estimated by exploring mixed and spatial models and pedigree information.

A mixed model approach was used to estimate variance components and heritabilities for resistance to powdery mildew, a wind-borne disease in strawberry. In order to improve precision in the statistical computations, spatial error control effects were included to account for systematic environmental variations in the large field trials. Pedigree information was included where feasible. Seedling families obtained from an incomplete 63-by-63 diallel cross were grown at six locations and scored subjectively for mildew attack three times during the growing season. The 63 parents included both European and American cultivars as well as advanced selections from various breeding programmes. A total of 298 full-sib families were realized, including 26 reciprocal families. No reciprocal differences were found. On a plot-mean basis, the broad-sense heritability was found to be intermediate, H(2) = 0.44-0.50, depending on whether the pedigree information was included in the model or not. The increase was mainly due to a substantial increase in the additive variance component. Likewise, the narrow-sense heritability increased from h(2) = 0.39 to h(2) = 0.45 when the pedigree information was included, while the ratio of the specific combining ability variance to the general combining ability variance fell from 13% to 10%. The predicted breeding values of the 63 parents demonstrate that important cultivars such as Elsanta and Korona are unlikely to produce progenies with a high degree of resistance. On the other hand, the Norwegian cultivar Solprins, the Canadian cultivar Kent and the Italian cultivar Patty appeared to give highly resistant progeny. At the full-sib level, the estimated disease scores ranged from 1.15 (Kent x Induka) to 4.19 (Cavendish x Avanta), revealing a huge range of variation for powdery mildew resistance available for selection.

Analysis of Variance↗

A mutation in PCSK9 causing autosomal-dominant hypercholesterolemia in a Utah pedigree.

Familial hypercholesterolemia results from mutations in the low-density lipoprotein (LDL) receptor or apolipoprotein B genes. We have previously reported the identification of a Utah autosomal-dominant hypercholesterolemia pedigree (kindred 1173) that did not show linkage to either of these loci (Hunt et al. 2000). Expansion of the pedigree and increased marker density within the region of interest have resulted in a multipoint LOD score of 9.6 and enabled us to decrease the size of the linked region to approximately 7.5 Mbp. In addition, we were able to identify additional families sharing the same microsatellite haplotype. While all haplotype carriers in kindred 1173 (K1173) are affected, the haplotype carriers within the newly identified families are unaffected, suggesting that the causal mutation in K1173 had occurred after divergence of these pedigrees from a common ancestor. Mutation screening of genes in the region identified a single nucleotide variant (G-->T) present on the K1173 haplotype that was not present on the same haplotype in the other kindreds. This variant results in a D374Y missense change in the gene PCSK9.

Female↗

Another pedigree with pure autosomal dominant spastic paraplegia (AD-FSP) from Tibet mapping to 14q11.2-q24.3.

The mutant in a family with autosomal-dominant spastic paresis in Northern Tibet was mapped by linkage analysis with several microsatellite markers to a gene locus at 14q11.2-q24.3, an area to which a few mutants leading to a condition with similar clinical signs have previously been mapped. The mutant observed in this pedigree probably arose de novo. Gene loci at 2p21-p24 and 15q, which have been found for other pedigrees with dominant spastic paresis, were excluded. The data in this pedigree do not contradict the hypothesis proposed by another group that there might be anticipation.

Adult↗

Scanning for MODY5 gene mutations in Chinese early onset or multiple affected diabetes pedigrees.

Mutation of HNF-1beta gene has been reported in early onset diabetes or MODY families and this gene has been defined as MODY5 gene. The aim of our study was to examine whether HNF-1beta mutation contribute to early onset or multiple affected diabetes pedigrees in Chinese. Molecular scanning of HNF-1beta gene promoter region, nine exons and flanking introns was performed in 154 unrelated probands from early onset and multiple affected diabetes Chinese pedigrees. The family members of probands with mutations or variants and 58 nondiabetics were also examined. Clinical examinations of renal morphology, renal function and beta-cell function were performed in the HNF-1beta gene mutation carriers and family members. Mutation of HNF-1beta gene causing the substitution S36F was found in two subjects of an early onset diabetic family. One carrier has early onset diabetes, renal function impairment and renal cyst, while the other has impaired glucose tolerance only. This is the first case of MODY5 gene mutation diabetes found in the Chinese. Three HNF-1beta variants were identified and no significant differences in allele frequencies for these variants were detected between the nondiabetic and diabetic groups. Nucleotide 66 of intron 8 of HNF-1beta gene was G in the Chinese population rather than A as noted in the GenBank sequence. These results suggest that HNF-1beta gene mutations may be associated with nondiabetic renal dysfunction and diabetes in Chinese, but they are responsible for only a small percentage of early onset or multiple affected diabetes pedigrees including MODY.

Adenine↗

Web-based detection of genotype errors in pedigree data.

For linkage analysis using pedigree data, it is important to eliminate contradictions concerning Mendelian inheritance from genotypic data. Such contradictions may derive from either genotyping errors or pedigree errors. We implemented an error-checking algorithm in a World Wide Web-based program that can be used through the Internet even by computer nonspecialists. This program, named Checkfam, uses two error-checking algorithms to detect and report contradictions concerning Mendelian inheritance. With this program, users can guess the causes of genotype errors (technical problems in genotyping, pedigree misrecording, or errors in input data concerning familial relationships). The present program will be useful to researchers for checking genotypic data and for preparing correct input files for linkage analysis.

Algorithms↗

Pedigree analysis of the 5' flanking region of the insulin gene in familial diabetes mellitus.

Non-insulin-dependent diabetes mellitus (NIDDM) has been reported to be associated with an insertion polymorphism in the 5' flanking region of the human insulin gene. We have attempted to examine linkage of this polymorphism to the phenotype of NIDDM by studying multiple pedigrees. We evaluated 142 individuals (120 white, 22 black), 80 of whom were from 7 pedigrees (5 white, 2 black) ranging in size from 4 to 37 members. Of these, 52 subjects had NIDDM, 10 had insulin-dependent diabetes mellitus (IDDM), and 80 were nondiabetics (ND). DNA was extracted from leukocytes and after digestion with Sst 1, and electrophoresis, the DNA was blotted to nitrocellulose filters and hybridized to a alpha 32P-labeled insulin gene probe. Two alleles of 6.0 and 7.6 kb in size were detected, the latter corresponding to the common previously described insertion polymorphism. In these families, the 7.6 kb allele occurred in 32 of 57 ND, 3 of 5 IDDM, and 10 of 18 NIDDM (P = 0.98). When sibships were analyzed the 7.6 kb allele occurred in 6 of 13 ND, 3 of 5 IDDM, and 8 of 12 NIDDM (P = 0.58). In examining 72 unrelated subjects, including 12 spouses from the pedigrees, the 7.6 kb allele was documented in 16 of 36 ND, 1 of 5 IDDM, and 16 of 31 NIDDM (P = 0.59). In these individuals and in the multiple families studied the insertion polymorphism flanking the insulin gene showed Mendelian inheritance and assorted independently of the phenotype of diabetes mellitus.

Adolescent↗

Nettleship's two pedigrees of retinitis pigmentosa: a historical postscript.

Two pedigrees of retinitis pigmentosa, originally published by Nettleship, are presented with extracts from his private correspondence. Affected descendants from the two families have been traced, in one family extending the pedigree to nine affected generations, and in the other providing an instance of male-to-male transmission in a pedigree previously considered as being possibly X-linked.

Adult↗

Recruitment of members of high-risk Utah pedigrees.

Cardiovascular Genetics Research Projects in Utah are designed to investigate genetic and environmental determinants of early coronary disease, stroke, and hypertension in population-based pedigrees. Early coronary disease is defined as the occurrence of documented coronary death or myocardial infarction before age 55. Detailed recruitment experience is reported for 2500 persons age 3-83 years in 98 high-risk pedigrees from three ascertainment groups: 1. Descendants of sibships with two or more stroke deaths before age 75. 2. Descendants of sibships with two or more coronary deaths before age 55. 3. First- and second-degree relatives of hypertensive and normotensive probands randomly selected from the Utah Hypertension Detection and Follow-up Program. A response rate of 94% of invited adults attending the first 4-hour clinic visit for detailed screening in 1980-1983 was achieved by multiple telephone, mail, and personal contacts and rescheduling of missed clinic appointments. For the same participants, a second screening cycle in 1983-1986 showed a 91% response of invited adults. Second visit response rates were examined within subgroups according to data collected at the first clinic visit. Below average response rates included 79% of persons with fewer than 12 years of education, 84% of current smokers, and 86% of divorced persons. Above average response rates included 93% of persons attending college and 95% of persons with total family income above $25,000. There were no differences in response according to sex or age. The average cost of recruitment was $59 per person and represented about 10% of the total budget for the High-Risk Pedigree Project.

Adolescent↗

Ophthalmologic findings in a large pedigree of 11778/Haplogroup J Leber hereditary optic neuropathy.

PURPOSE: To report the ophthalmologic characteristics of a newly identified seven-generation pedigree of 11778/Haplogroup J Leber hereditary optic neuropathy consisting of 328 living individuals, 111 of whom are maternally related. DESIGN: Observational population cohort study. METHODS: This prospective study of a large Brazilian Leber hereditary optic neuropathy pedigree was carried out as a field investigation in Brazil. We describe the ophthalmologic findings of 192 eyes from 96 maternally related individuals of this pedigree. Spouses were used as control subjects. We conducted comprehensive neuro-ophthalmologic examinations with psychophysical tests, Humphrey visual fields, and fundus photographs. We also correlated the ophthalmologic findings with the previously published epidemiologic assessment of risk factors. RESULTS: We examined 76 carriers and 20 affected individuals. The affected individuals showed severe disease with a mean visual acuity of 2.04 logarithm of the minimal angle of resolution and without evidence of recovery. All the affected individuals showed diffuse optic atrophy with a cup-to-disk ratio greater than 0.5 in 55% of cases. Moreover, among Affected individuals, smokers had a poorer visual acuity (P =.002). Among carriers there were several subclinical abnormalities, including microangiopathy, swelling of nerve fibers, and visual field abnormalities that did not correlate with tobacco or alcohol consumption. CONCLUSIONS: Our results demonstrate a significant influence of environmental risk factors, particularly smoking, for developing Leber hereditary optic neuropathy and for the severity of its clinical expression. However, smoking did not correlate with the subclinical abnormalities detected in carriers. Moreover, subclinical abnormalities were equally distributed between gender.

Adolescent↗

Genome-wide scan and conditional analysis in bipolar disorder: evidence for genomic interaction in the National Institute of Mental Health genetics initiative bipolar pedigrees.

BACKGROUND: In 1989 the National Institute of Mental Health began a collaborative effort to identify genes for bipolar disorder. The first 97 pedigrees showed evidence of linkage to chromosomes 1, 6, 7, 10, 16, and 22 (Nurnberger et al 1997). An additional 56 bipolar families have been genotyped, and the combined sample of 153 pedigrees studied. METHODS: Three hierarchical affection status models were analyzed with 513 simple sequence repeat markers; 298 were common across all pedigrees. The primary analysis was a nonparametric genome-wide scan. We performed conditional analyses based on epistasis or heterogeneity for five regions. RESULTS: One region, on 16p13, was significant at the genome-wide p <.05 level. Four additional chromosomal regions (20p12, 11p15, 6q24, and 10p12) showed nominally significant linkage findings (p </=.01). Conditional analysis assuming epistasis identified a significant increase in linkage at four regions. Families linked to 6q24 showed a significant increase in nonparametric logarithms of the odds (NPL) scores at 5q11 and 7q21. Epistasis also was observed between 20p12 and 13q21, and 16p13 and 9q21. CONCLUSIONS: The findings are presented in rank order of nominal significance. Several of these regions have been previously implicated in independent studies of either bipolar disorder or schizophrenia. The strongest finding is at 16p13 at D16S748 with an NPL of 3.3, there is evidence of epistasis between this locus and 9q21. Application of conditional analyses is potentially useful in larger sample collections to identify susceptibility genes of modest influence that may not be identified in a genome-wide scan aimed to identify single gene effects.

Bipolar Disorder↗

Attempted suicide in bipolar disorder pedigrees: evidence for linkage to 2p12.

BACKGROUND: We are interested in identifying susceptibility genes that predispose subjects to attempted suicide. METHODS: We conducted a secondary analysis of genome-wide linkage data from 162 bipolar pedigrees that incorporated attempted suicide as a clinical covariate. RESULTS: The strongest covariate-based linkage signal was seen on 2p12 at marker D2S1777. The logarithm of odds (LOD) score at marker D2S1777 rose from 1.56 to 3.82 after inclusion of the suicide covariate, resulting in significant chromosome-wide empirically derived p-values for the overall linkage finding (p = .01) and for the change in LOD score after the inclusion of the covariate (p = .02). CONCLUSIONS: The finding on chromosome 2 replicates results from two previous studies of attempted suicide in pedigrees with alcohol dependence and in pedigrees with recurrent early-onset depression. Combined, these three studies provide compelling evidence for a locus influencing attempted suicide on 2p12.

Bipolar Disorder↗

Identification of SQSTM1 mutations in familial Paget's disease in Australian pedigrees.

We have conducted a genome-wide scan on a pedigree containing 372 adult members, of whom 49 have PDB. In the present study, we report linkage of a large pedigree to the PDB3 region on chromosome 5q35-qter with a peak multipoint LOD score of 6.77. Sequestosome 1 (SQSTM/p62) has been identified as the causative PDB gene in this region. Six sequestosome 1 mutations have been described to date. Four mutations have been identified in exon 8, 1210delT and 1215delC both resulting in premature stop codon at amino acid 394, 1215C to T (P392L), 1224insT (E396X), one mutation in exon 7, 1200C to T (P387L) and a G to A splice junction mutation at IVS7+1. These mutations cluster in the C terminus of the protein and are predicted to disrupt the ubiquitin binding properties of sequestosome 1. Sequence analysis of the gene encoding sequestosome 1 revealed a single base pair deletion (1215delC) segregating with the majority of affected members in the pedigree. This deletion introduces a stop codon at position 394, resulting in premature termination of the protein (L394X) and loss of the ubiquitin-associated binding domain. Screening of affected members from 10 further PDB families identified the previously reported P392L mutation in one family. No SQSTM1/p62 coding mutations were found in the remaining 9 families or in 113 age-matched controls.

Adaptor Proteins, Signal Transducing↗