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Familial hemiplegic migraine: a clinical comparison of families linked and unlinked to chromosome 19.DMG RG.

We compared the clinical characteristics of 46 patients from three unrelated families with familial hemiplegic migraine (FHM) linked to chromosome 19, with those of 20 patients from two families with FHM not linked to chromosome 19. We found no significant differences for age at onset, frequency and duration of attacks, duration of the paresis, and occurrence of basilar migraine symptoms. In the linked families, significantly more patients reported unconsciousness during attacks (39% vs 15%; p < 0.05) and provocation of attacks by mild head trauma (70% vs 40%; p < 0.05). In one linked family patients also displayed chronic progressive cerebellar ataxia, whereas in one unlinked family benign infantile convulsions occurred in addition to FHM. Interestingly, so far an association with cerebellar ataxia was only described in chromosome 19-linked families. FHM linked to chromosome 19 and FHM unlinked to chromosome 19 do not differ with respect to clinical features.

Adolescent↗

Single-family versus multi-family introductions.

The early success of plant introduction as a function of source material and habitat quality was tested in Arnica montana to determine whether different introduction strategies could affect plant viability of the introduced population. Plants originating from related (single-family introductions) and unrelated (multi-family introductions) individuals were introduced into undisturbed sites and into sites which were limed, turf cut, or both turf cut and limed. For four consecutive years, we analysed plant performance by measuring survival time, growth, and reproductive capacity. Introduction success was found to be strongly affected by habitat quality. Turf cutting in combination with additional liming significantly increased reproductive capacity and stimulated early flowering. To restore eutrophic and acidified soil conditions, turf cutting with additional liming prior to introduction is recommended. Furthermore, a significant effect of multi-family introductions was observed. Multi-family introductions showed higher introduction success compared to single-family introductions. Although the long-term effects of multi-family introductions will emerge after several generations, the preliminary results suggest multi-family introductions as the most successful introduction strategy.

Arnica↗

Silkmoth chorion multigene families constitute a superfamily: comparison of C and B family sequences.

We have characterized a new family of silkmoth chorion genes, called C, which is distinct from previously characterized A and B families. The amino acid compositions of 18 purified C proteins have been determined. Three subgroups are recognized on the basis of compositional similarities and may correspond to distinct gene families or subfamilies. The sequences of two overlapping cDNA clones have been determined in their entirety and shown to correspond to a C-specific sequence. Obvious homology is observed between the middle portions of the C sequence and previously characterized B sequences. By contrast, the arms of the C sequence share no significant similarities either with each other or with the corresponding arms of B sequences. Thus, the same tripartite structure originally observed in A and B family sequences is also present in the C family and may have functional significance. Secondary structure prediction of the C sequence is presented and supports this conclusion. The observed homology between C and B family sequences clearly establishes that silkmoth chorion multigene families constitute a superfamily.

Amino Acid Sequence↗

Familial thrombophilia: clinical and molecular analysis of Swedish families with inherited resistance to activated protein C or protein S deficiency.

This report describes the characterization of Swedish families with inherited resistance to activated protein C (APC resistance) and/or protein S deficiency, two genetic disorders associated with functional impairment of the protein C anticoagulant pathway. The APC resistance phenotype was linked to the factor V gene locus in a kindred with independent inheritance of APC resistance and protein S deficiency. A point mutation changing Arg506 to a Gln (FV:Q506) in the factor V gene was the cause of APC resistance. In studies of 50 families with hereditary APC resistance, the FV:Q506 mutation was identified in 94% (47/50) of the families, and the thrombotic risk was found to be dependent on the factor V genotype. Moreover, 18 families with hereditary deficiency of free protein S were investigated. Type I protein S deficiency (low free and total protein S) and type III deficiency (low free but normal total protein S) coexisted in 78% (14/18) of the families, suggesting the two types to be phenotypic variants of the same genetic disorder. Deficiency of free protein S was caused by equimolar relationship between protein S and beta-chain containing isoforms of C4BP. Though protein S deficiency was a strong risk factor for thrombosis, the FV:Q506 mutation was identified as an additional genetic risk factor in 39% of the families. Thus, familial thrombophilia is a multiple gene disorder. The thrombophilic tendency associated with APC resistance or protein S deficiency was related to increased levels of prothrombin fragment 1 + 2, reflecting increased activation of the common coagulation pathway.

Adolescent↗

Linkage analysis of chromosome 1q markers in 136 prostate cancer families. The Cancer Research Campaign/British Prostate Group U.K. Familial Prostate Cancer Study Collaborators.

Prostate cancer shows evidence of familial aggregation, particularly at young ages at diagnosis, but the inherited basis of familial prostate cancer is poorly understood. Smith et al. recently found evidence of linkage to markers on 1q, at a locus designated "HPC1," in 91 families with multiple cases of early-onset prostate cancer. Using both parametric and nonparametric methods, we attempted to confirm this finding, in 60 affected related pairs and in 76 families with three or more cases of prostate cancer, but we found no significant evidence of linkage. The estimated proportion of linked families, under a standard autosomal dominant model, was 4%, with an upper 95% confidence limit of 31%. We conclude that the HPC1 locus is responsible for only a minority of familial prostate cancer cases and that it is likely to be most important in families with at least four cases of the disease.

Chromosomes, Human, Pair 1↗

In Swedish families with hereditary prostate cancer, linkage to the HPC1 locus on chromosome 1q24-25 is restricted to families with early-onset prostate cancer.

Prostate cancer clusters in some families, and an estimated 5%-10% of all cases are estimated to result from inheritance of prostate cancer-susceptibility genes. We previously reported evidence of linkage to the 1q24-25 region (HPC1) in 91 North American and Swedish families each with multiple cases of prostate cancer (Smith et al. 1996). In the present report we analyze 40 (12 original and 28 newly identified) Swedish families with hereditary prostate cancer (HPC) that, on the basis of 40 markers spanning a 25-cM interval within 1q24-25, have evidence of linkage. In the complete set of families, a maximum two-point LOD score of 1.10 was observed at D1S413 (at a recombination fraction [theta] of.1), with a maximum NPL (nonparametric linkage) Z score of 1.64 at D1S202 (P=.05). The evidence of linkage to this region originated almost exclusively from the subset of 12 early-onset (age <65 years) families, which yielded a maximum LOD score of 2.38 at D1S413 (straight theta=0) and an NPL Z score of 1.95 at D1S422 (P=.03). Estimates from heterogeneity tests suggest that, within Sweden, as many as 50% of early-onset families had evidence of linkage to the HPC1 region. These results are consistent with the hypothesis of linkage to HPC1 in a subset of families with prostate cancer, particularly those with an early age at diagnosis.

Age of Onset↗

Temperature-sensitive RB mutations linked to incomplete penetrance of familial retinoblastoma in 12 families.

The tumor-suppressor activity of the retinoblastoma protein (RB) is encoded within a protein-binding ("pocket") domain that is targeted for mutations in all cases of familial retinoblastoma and in many common adult cancers. Although familial retinoblastoma is a paradigm for a highly penetrant, recessive model of tumorigenesis, the molecular basis for the phenotype of incomplete penetrance of familial retinoblastoma is undefined. We studied the RB pocket-binding properties of three independent, mutant RB alleles that are present in the germline of 12 kindreds with the phenotype of incomplete penetrance of familial retinoblastoma. Each arises from alterations of single codons within the RB pocket domain (designated "delta 480," "661W," or "712R"). Under the same conditions, we studied the properties of wild-type (WT) RB, an RB point mutant isolated from a lung carcinoma sample (706F) and an adjacent, in vitro-generated point mutant (707W). The delta 480, 661W, and 712R mutants lack pocket protein-binding activity in vitro but retain the WT ability to undergo cyclin-mediated phosphorylation in vivo. Each of the low-penetrant RB mutants exhibits marked enhancement of pocket protein binding when the cells are grown at reduced temperature. In contrast, in this temperature range, no change in binding activity is seen with WT RB, the 706F mutant, or the 707W mutant. We have demonstrated that many families with incomplete penetrance of familial retinoblastoma carry unstable, mutant RB alleles with temperature-sensitive pocket protein-binding activity. The variable frequency for tumor development in these families may result from reversible fluctuations in a threshold level of RB pocket-binding activity.

Alleles↗

Mutational and haplotype analyses of families with familial partial lipodystrophy (Dunnigan variety) reveal recurrent missense mutations in the globular C-terminal domain of lamin A/C.

Familial partial lipodystrophy (FPLD), Dunnigan variety, is an autosomal dominant disorder characterized by marked loss of subcutaneous adipose tissue from the extremities and trunk but by excess fat deposition in the head and neck. The disease is frequently associated with profound insulin resistance, dyslipidemia, and diabetes. We have localized a gene for FPLD to chromosome 1q21-q23, and it has recently been proposed that nuclear lamin A/C is altered in FPLD, on the basis of a novel missense mutation (R482Q) in five Canadian probands. This gene had previously been shown to be altered in autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD-AD) and in dilated cardiomyopathy and conduction-system disease. We examined 15 families with FPLD for mutations in lamin A/C. Five families harbored the R482Q alteration that segregated with the disease phenotype. Seven families harbored an R482W alteration, and one family harbored a G465D alteration. All these mutations lie within exon 8 of the lamin A/C gene-an exon that has also been shown to harbor different missense mutations that are responsible for EDMD-AD. Mutations could not be detected in lamin A/C in one FPLD family in which there was linkage to chromosome 1q21-q23. One family with atypical FPLD harbored an R582H alteration in exon 11 of lamin A. This exon does not comprise part of the lamin C coding region. All mutations in FPLD affect the globular C-terminal domain of the lamin A/C protein. In contrast, mutations responsible for dilated cardiomyopathy and conduction-system disease are observed in the rod domain of the protein. The FPLD mutations R482Q and R482W occurred on different haplotypes, indicating that they are likely to have arisen more than once.

Alleles↗

Understanding familial and non-familial renal cell cancer.

Molecular genetic analysis of familial and non-familial cases of conventional renal cell carcinoma (RCC) revealed a critical role(s) for multiple genes on human chromosome 3. For some of these genes, e.g. VHL, such a role has been firmly established, whereas for others, definite confirmation is still pending. Additionally, a novel role for constitutional chromosome 3 translocations as risk factors for conventional RCC development is rapidly emerging. Also, several candidate loci have been mapped to other chromosomes in both familial and non-familial RCCs of distinct histologic subtypes. The MET gene on chromosome 7, for example, was found to be involved in both forms of papillary RCC. A PRCC-TFE3 fusion gene is typically encountered in t(X;1)-positive non-familial papillary RCCs and results in abrogation of the cell cycle mitotic spindle checkpoint in a dominant-negative fashion, thus leading to RCC. Together, these data turn human RCC into a model system in which different aspects of both familial and non-familial syndromes may act as novel paradigms for cancer development.

Carcinoma, Renal Cell↗

Origin of the Alu family: a family of Alu-like monomers gave birth to the left and the right arms of the Alu elements.

The Alu dimeric elements are a common feature of the primate genomes, where they constitute a family of related sequences (1). The identification of a free left Alu monomer (FLAM) family plus a free right Alu monomer (FRAM) family suggests that the dimeric structure results from the fusion of a FLAM sequence with a FRAM sequence (2). Here, we describe a very old Alu-like monomeric family, referred to as FAM for fossil Alu monomer. This family arose from a 7SL RNA sequence and gave birth to the FLAM and FRAM families. From the results obtained, the evolution of the Alu family can be subdivided into two phases. The first phase, which involves only monomeric elements, is characterized by deep remodelling of the progenitor sequences and ends with the appearance of the first Alu dimeric element through the fusion of a FLAM and a FRAM element. The second phase, still in progress, starts with the first Alu dimeric element. This phase is characterized by the stabilization of the progenitor sequences.

Base Sequence↗

Novel COL4A4 splice defect and in-frame deletion in a large consanguine family as a genetic link between benign familial haematuria and autosomal Alport syndrome.

BACKGROUND: Alport syndrome (AS) is a common hereditary cause for end-stage renal failure due to a defect in type IV collagen genes. The molecular pathogenesis of benign familial haematuria (BFH) is not fully understood. Evidence from linkage analyses and mutation studies point to a role of the COL4A3/COL4A4 genes. The present study describes molecular changes of the COL4A4 gene that cause both diseases: autosomal recessive AS and BFH in a consanguine family with a 400-year-old history of haematuria. METHODS: RNA and DNA were isolated and analysed by RT-PCR, PCR, DNA and cDNA sequencing, and Southern blotting. Evaluation of family members comprised creatinine clearence, urine analysis, audiometry and past medical history. RESULTS: Forefathers of this family moved to a German village in the 17th century. Sporadic episodes of macrohaematuria have been reported ever since. Numerous family members with haematuria including the parents of the index family were heterozygous for a splice defect eliminating exon 25 from the alpha4(IV) cDNA. The daughter (15 years old, creatinine clearence 27 ml/min, proteinuria 5 g/day, hearing loss) was homozygous for the mutation, while the son (22 years old, creatinine clearance 68 ml/min, proteinuria 11 g/day, hearing loss, splitted and thickened glomerular basement membrane) was heterozygous. Further analysis showed a second mutation, an 18 bp in-frame deletion in exon 25, for which numerous family members were heterozygous, and both children were homozygous. CONCLUSIONS: The COL4A4 splice defect causes BFH-phenotype in heterozygous, and AS in homozygous state. The clinical spectrum of heterozygous individuals reaches from macrohaematuria, intermittent microhaematuria to isolated deafness. The 18 bp in-frame deletion aggravates the phenotype in the compound heterozygous son. These results give further evidence that BFH and autosomal AS are in fact both type IV collagen diseases.

Adolescent↗

Effects of similarities in lifestyle habits on familial aggregation of high density lipoprotein and low density lipoprotein cholesterol: the NHLBI Family Heart Study.

It is generally assumed that familial aggregation of lipids relates to both genetic and shared environmental factors. To determine the degree to which familial similarities in lifestyle habits explain familial aggregation of high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, the authors analyzed 1994-1996 data from 2,284 US adult participants in the National Heart, Lung, and Blood Institute Family Heart Study. For men and women, respectively, HDL cholesterol correlated with alcohol consumption (r = 0.27, p < 0.001; r = 0.21, p < 0.001), exercise (r = 0.06, p = 0.05; r = 0.10, p = 0.002), and smoking (r = -0.09, p = 0.005; r = -0.13, p < 0.001). There was strong familial aggregation of HDL cholesterol (parent-child, r = 0.32; sibling-sibling, r = 0.29), but less than 10% was explained by lifestyle habits. For LDL cholesterol, weak correlations were found for intake of total fat (r = 0.06, p = 0.07) and fruits/vegetables (r = -0.09, p = 0.005) among men and for smoking (r = 0.10, p = 0.002) among women. LDL cholesterol correlated strongly among family members (parent-child, r = 0.24; sibling-sibling, r = 0.31), but essentially none of this aggregation related to the lifestyle factors studied. This study suggests that lifestyle factors have little effect on the familial aggregation of HDL and LDL cholesterol.

Adult↗

Familial aggregation of environmental risk factors and familial aggregation of disease.

Almost all human diseases have been shown to aggregate familially to some degree. This familiality is generally taken as evidence for the existence of a genetic etiologic mechanism or environmental factors common to family members, or a combination of both. It has been argued that for a disease with strong familial aggregation, environmental risk factors alone are unlikely to account for such strong aggregation, unless the presumed environmental risk factors are associated with enormous risk. This paper revisits this issue through the use of a novel statistical model. Ascertainment bias aside, the author demonstrates that familial aggregation could be explained by multiple interactive risk factors, each of which may confer a low disease risk and thus contribute only a minuscule portion to disease familiality. For example, two correlated risk factors (r=0.5), each with a relative risk of 5 and acting multiplicatively, could give rise to a sibling relative risk of 1.96. Therefore, it may not be sufficient to argue for a genetic component for a disease based solely on the notion that no high risk environmental factors have been found. In view of this, there is a need to examine carefully the roles of multiple environmental risk factors in disease familiality.

Bias↗

Clinical and genetic study on a new Chinese family with benign familial infantile seizures.

Three loci for benign familial infantile seizures (BFIS, traditionally named benign familial infantile convulsions) have been mapped to the chromosome regions of 19q12-13.1, 2q24, and 16p12-q12. We characterized the clinical features of a newly discovered Chinese family with BFIS and investigated whether it is linked to these loci. A four-generation Chinese family was investigated and nineteen family members were examined. Fourteen microsatellite markers covering the three BFIS loci on the chromosome regions of 19q12-13.1, 2q24, and 16p12-q12 were genotyped. Linkage analysis was performed. The main clinical features of our patients include onset of afebrile seizures between 3 and 10 months, normal psychomotor development, normal interictal electroencephalogram (EEG), and autosomal dominant inheritance. Magnetic resonance imaging (MRI) changes were found in the proband. Two-point LOD scores are < -2.0 at the recombination rate of 0.0 for all the markers on the 2q24 region. Multipoint LOD scores are < -3.0 for the regions of 19q12-13.1 and 16p12-q12. Linkage analysis showed no evidence that the disease gene of this BFIS family is linked to the chromosome regions previously identified as the critical regions of the disease. Another chromosome region harboring the disease gene may exist in the new Chinese family.

Adult↗

Age of onset in familial adenomatous polyposis: heterogeneity within families and among APC mutations.

Heterogeneity among and within FAP pedigrees for the age of symptom onset and the age at death from colorectal cancer was studied in a sample of 583 patients of the Italian Polyposis Registry. The among pedigree variation was largely explained by clustering of families in two groups, 'early FAP' (most colorectal cancer deaths below 45 years of age) and 'late FAP' families (most deaths above age 45). The within-family variation was explained by a marked phenomenon of anticipation (15 years per generation, on the average), possibly not due to ascertainment bias. We then considered the pedigrees with identified mutation in the APC gene. Six families shared a common deletion at codon 1309 and showed the early FAP phenotype. Two families shared a mutation at codon 1061 and revealed the late FAP phenotype. Another two families (codons 453 and 302) clustered with the late FAP group, whereas a family with mutation at codon 835 clustered with the early FAP group. We suggest that there are at least two classes of mutations in the APC gene with different consequences at the phenotypic level. It seems that there are several critical points within the APC protein sequence at which truncation causes a more aggressive disease than truncation at other points.

Adenomatous Polyposis Coli↗

Florid oral manifestations in an atypical familial adenomatous polyposis family with late presentation of colorectal polyps.

Early identification and prophylactic surgery are essential in preventing development of malignancy in colorectal polyps in familial adenomatous polyposis (FAP). Previous studies indicate a 100% cumulative risk of developing colonic polyps in individuals with FAP by the age of 34 yr. However, we have previously reported late-onset and non-penetrance of polyposis in four families. We describe here in detail one of these families with florid oral manifestations detectable on panoramic radiography of the jaws, which were instrumental in the diagnosis of FAP in the index patient and for ascertainment of her family for screening. The pathological adenomatous polyposis coli (APC) gene mutation in this family was shown to segregate with dento-osseous changes. Panoramic jaw radiography is a common examination carried out prior to dental or oral surgical procedures. This case illustrates the importance of appropriate investigations, including family history and colonoscopy, even in relatively older patients with radiological findings such as those described here and in members of their families at risk of FAP.

Adenomatous Polyposis Coli↗

Familial hiatal hernia in a large five generation family confirming true autosomal dominant inheritance.

BACKGROUND: Familial hiatal hernia has only rarely been documented. AIMS: To describe the pattern of inheritance of familial hiatal hernia within an affected family. SUBJECTS: Thirty eight members of a family pedigree across five generations. METHODS: All family members were interviewed and investigated by barium meal for evidence of a hiatal hernia. RESULTS: Twenty three of 38 family members had radiological evidence of a hiatal hernia. No individual with a hiatal hernia was born to unaffected parents. In one case direct male to male transmission was shown. CONCLUSIONS: Familial inheritance of hiatal hernia does occur. Evidence of direct male to male transmission points to an autosomal dominant mode of inheritance.

Adolescent↗

Systematic family screening for familial hypercholesterolemia in Iceland.

OBJECTIVE: This study compares a novel approach using systematic family screening for patients in Iceland who have familial hypercholesterolemia (FH) with conventional proband screening and assesses the sensitivity and specificity of diagnosing FH by cholesterol measurements compared with mutational testing of family members. METHODS AND RESULTS: Probands with the I4T+2C mutation were traced to common ancestors. A downtracing of each family lineage was performed back to the oldest living offspring (key individuals); these individuals were recruited for cholesterol measurement and mutation testing. The sensitivity and specificity of cholesterol measurements was assessed against mutational analysis. Eleven probands clustered into 4 families. There were 364 key individuals identified among their descendants. Eighty-four percent responded, and 11% were positive for the mutation. There were 78 offspring of the positive key individuals, and 40 of those were carriers. Compared with use of the conventional first-degree relative approach, an additional 19% of FH individuals, including key individuals and their descendants, were identified. As diagnostic criteria, cholesterol measurements in the families had 95% specificity and 94% sensitivity. CONCLUSIONS: Tracing FH probands to common ancestors and screening the oldest offspring in each family lineage adds considerably to the conventional method of FH screening (testing first-degree relatives). This may have relevance in other founder populations.

Adolescent↗