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Arrest of human oocytes during meiosis I in two sisters of consanguineous parents: first evidence for an autosomal recessive trait in human infertility: Case report.

Two sisters descended from consanguineous parents underwent unsuccessful IVF treatments. Their oocytes showed neither a first or second polar body, nor pronuclei. After cytogenetic preparation, all oocytes were characterized by condensed maternal metaphase I chromosomes and premature chromosome condensation of the sperm nucleus. Both women exhibited a normal female karyotype (46,XX). The pedigree of the family revealed two other sisters who had delivered children, but also two brothers who had been married for several years without children. There is a strong indication for an autosomal recessive trait responsible for the idiopathic infertility due to the expression of a rare recessive allele inherited from common ancestors. However, neither the mechanism of metaphase I arrest nor the gene(s) involved in this arrest are known in the case of our patients. We discuss molecular mechanism(s) derived from animal models that might be involved in this inherited disorder in human oocytes.

Adult↗

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↗

A homozygous HAMP mutation in a multiply consanguineous family with pseudo-dominant juvenile hemochromatosis.

Juvenile hemochromatosis (JH) is an autosomal recessive condition that leads to significant morbidity due to early onset systemic iron overload. The majority of families with JH link to chromosome 1q and were recently found to have mutations in the HFE2 gene encoding hemojuvelin; however, several JH families have been reported to have mutations in the HAMP gene encoding hepcidin. Here, we report a multiply consanguineous family with a father and daughter showing iron overload consistent with JH. Sequence analysis of HAMP revealed homozygosity for amino acid substitution C78T due to a c.233G > A mutation. This mutation disrupts one of eight highly conserved cysteines that are believed to be critical for the function of the active enzyme. This finding adds support to the importance of the role of these conserved cysteines in the activity of hepcidin.

Adult↗

Further delineation of the Cohen syndrome; report on chorioretinal dystrophy, leukopenia and consanguinity.

Six new patients with the Cohen syndrome are reported from Finland and 25 published cases from elsewhere are reviewed. New findings are consanguinity among two pairs of parents, granulocytopenia, and marked ophthalmological changes: decreased visual acuity, hemeralopia, constricted visual fields, chorioretinal dystrophy with bull's-eye-like maculae and pigmentary deposits, optic atrophy, and isoelectric electroretinogram. Previously known features of the Cohen syndrome (non-progressive mental retardation, short stature, microcephaly, peculiar facies, slender hands and feet, floppiness, delayed puberty) are confirmed or revised. The ophthalmological features merit attention in the previous and future suspected cases of the Cohen syndrome. Autosomal recessive inheritance can be taken for granted.

Abnormalities, Multiple↗

Oculocerebral syndrome with hypopigmentation (Cross syndrome). Report of two siblings born to consanguineous parents.

In this report we describe two siblings, a 17-year-old male and his deceased sister, born to consanguineous parents, and presenting an oculocerebral syndrome with hypopigmentation as first delineated by Cross in 1967. In addition to the cutaneous hypopigmentation, both presented deep mental retardation and spastic tetraplegia with athetoid movements. A remarkable finding in this family is that a third sibling, an otherwise normal 23-year-old male, presents the same hypopigmentation with white-grey hair colour as his two severely affected siblings.

Adolescent↗

Consanguineous marriages in the Turkish population.

This study of 55,175 marriages in Turkey, conducted from 1970 to 1987, showed an overall rate of consanguineous marriage of 21.21% (mostly first-cousin liaisons) and an inbreeding coefficient of 0.0064532. However, considerable differences between areas are apparent.

Adolescent↗

Achalasia microcephaly syndrome in a patient with consanguineous parents: support for a.m. being a distinct autosomal recessive condition.

A 4 9/12-year-old boy with achalasia microcephaly syndrome (AMS), born to a consanguineous couple, is reported. Comparative analysis of this case and the patients previously described in a Mexican family supports the notion that the syndrome is a distinct autosomal recessive condition. It is interesting that the area of origin and ethnicity of both the present and the previously reported cases is northwest Mexico.

Abnormalities, Multiple↗

Consanguineous marriages among parents of Down patients.

In order to reveal if there is an effect on the genesis of meiotic- or early zygotic non-disjunctions, data related to 1598 Down syndrome patients from 1578 families studied in five different genetic centers in Turkey are reported. Parental consanguinity and the inbreeding coefficient were found to be lower among patients of 21-trisomics than in parents without Down offspring. It was concluded that available information does not support the presence of a "non-disjunction gene" in man.

Consanguinity↗

Autosomal recessive retinitis pigmentosa locus maps on chromosome 1q in a large consanguineous family from Pakistan.

A large Pakistani family with several consanguineous marriages is described, in which autosomal recessive retinitis pigmentosa is segregating. Linkage studies revealed close linkage between the disease locus and six loci on chromosome 1q (D1S158, F13B, D1S422, D1S412, D1S413, and D1S53) with maximum lod scores ranging from 0.988-4.657 at theta = 0.065-0.235. However, the analysis of individual nuclear families showed very close linkage without recombination in three branches and several recombinants and negative lod scores throughout in the fourth branch. These results strongly suggest that mutations of two different genes are responsible for the disease in the 'linked' and 'unlinked' branches. Parallel to the linkage heterogeneity, clear phenotypic differences have been observed among the 'linked' and 'unlinked' parts. Our findings demonstrate that in case of recessive disorders the possibility of non-allelic genetic heterogeneity should always be considered, even within the same kindred and in genetic isolates if a largely extended pedigree is analysed.

Chromosome Mapping↗

Skipping of exon 12 as a consequence of a point mutation (1898 + 5G-->T) in the cystic fibrosis transmembrane conductance regulator gene found in a consanguineous Chinese family.

A point mutation (1898 + 5G-->T) located five base pairs downstream from the donor splice site in intron 12 of the CFTR gene has been identified in a consanguineous CF patient of Chinese origin. To determine if this nucleotide substitution could affect mRNA splicing, PCR analysis was performed with RNA isolated from the lymphoblastoid cell line of the mother of the deceased patient. While exon 12-minus transcript was detected in this sample, it was also found in individuals without 1898 + 5G-->T, albeit in a smaller proportion. Using a sequence polymorphism associated with each of the two alleles in the mother, however, we showed that mutant transcript was almost exclusively produced by the 1898 + 5G-->T allele. Skipping of exon 12 would result in the deletion of 29 amino acids from the first nucleotide binding domain of CFTR, rendering the protein non-functional. The possibility of a low level (< or = 2.5%) of normal transcript from the mutant allele cannot be excluded and it may explain the pancreatic sufficient phenotype of the patient. The 1898 + 5G-->T mutation was found in two other CF patients of Chinese origin, but it was not detected in 192 CF chromosomes of Caucasian origin and 30 other chromosomes from Chinese individuals without a family history of CF.

Base Sequence↗

Novel mutations in the EXT1 gene in two consanguineous families affected with multiple hereditary exostoses (familial osteochondromatosis).

Multiple hereditary exostoses (HME) is an autosomal dominant developmental disorder exhibiting multiple osteocartilaginous bone tumors that generally arise near the ends of growing long bones. Here, we report two large consanguineous families from Pakistan, who display the typical features of HME. Affected individuals also show a previously unreported feature--bilateral overriding of single toes. Analysis using microsatellite markers for each of the known EXT loci, EXT1, EXT2, and EXT3 showed linkage to EXT1. In the first family, mutation analysis of the EXT1 gene revealed that affected individuals were heterozygous for an in-frame G-to-C transversion at the conserved splice donor site in intron 1. This mutation is predicted to disrupt splicing of the first intron and produce a frameshift that leads to a premature termination codon. In the second family, an insertion of an A in exon 8 is predicted to produce a frameshift at codon 555 followed by a premature termination, a further 10 codons downstream. In both families, an increased number of affected male subjects were observed. In affected females in family 2, phenotypic variability and incomplete penetrance were noted.

Base Sequence↗

Testicular tumors in non-twin brothers from a consanguineous marriage.

Malignant testicular tumors occurring in non-twin brothers are reported. Both of the brothers suffered from amentia and epilepsy and were the product of a consanguineous marriage. One brother presented with teratocarcinoma and the other seminoma. With a review of the literature, genetic roles in the etiology of testicular neoplasia are discussed.

Adolescent↗

The genotypic distribution of relatives of homozygotes when consanguinity is present.

A correction is made to an expression given by Jacquard (1968, 1972a,b) for the genotypic distribution of a relative of a given homozygote when consanguinity is present. The correction will necessarily be small either if the allele present in the given homozygote has a frequency of near unity, or if the coefficient of inbreeding of the given homozygote is small.

Alleles↗

Cerebro-hepato-renal syndrome with parental consanguinity.

A case of cerebro-hepato-renal syndrome with some unusual features is reported. The neuropathological findings are described in detail. Electronmicroscopy showed astrocytes in the demyelinated areas of the brain to contain granules composed of laminated osmiophilic material. These structures could be abnormal mitochondria. The parental consanguinity in this case would further support an autosomal recessive mode of inheritance.

Astrocytes↗

Prevalence and type of cerebral palsy in a British ethnic community: the role of consanguinity.

Little is known about the prevalence of cerebral palsy (CP) within ethnic subgroups born in Britain. The Yorkshire Regional Cerebral Palsy Register has ascertained all cases of CP in children born within the Regional Health Authority boundary in 1985 to 1987 inclusive and diagnosed by 5 years of age. Birth registrations recorded by ethnic subgroups allowed us to determine the prevalence of CP within the Bradford District Health Authority (BDHA) boundaries by Asian and non-Asian ethnic subgroups. All the children with CP in BDHA were examined by one individual and careful family pedigrees recorded. We noted that BDHA had a high prevalence of CP; 3.87 to 4.16 per 1000. The prevalences in the non-Asian and Asian populations were 3.18, and between 5.48 and 6.42, per 1000, respectively. This difference was statistically significant (P = 0.03). First cousin marriages occurred in 15 of the 39 Asian families (51.7%) and nine of these families had another first or second degree family member with a similar type of CP to the index child. There was no consanguinity in the non-Asian families. These data highlight the increased need for services in some ethnic populations living in Britain and the likely genetic aetiology of a significant proportion of cases of CP in Asian families.

Cerebral Palsy↗

Aetiological factors and prevalence of severe mental retardation in children in a Swedish municipality: the possible role of consanguinity.

The prevalence of severe mental retardation (SMR) was studied in one of the 24 suburban municipalities in Stockholm. The study area had a high proportion of non-European nationals. The study population comprised 14138 children born between 1979 and 1992 who resided in this municipality on the census day, 31 December 1995. The total prevalence of SMR was 4.5 per 1000, being 3.7 per 1000 and 5.9 per 1000 in the European and in the non-European population, respectively. The majority of cases (66%) had a definite prenatal origin. Down syndrome was the cause in 20%. Six families (10%) had at least two children with SMR. It was concluded that the prevalence was higher than in previous Swedish studies. Many cases were attributed to genetic factors. Consanguineous marriages were assumed to be a factor of importance in the distribution of aetiologies. Demographic differences between areas in Sweden must be considered when planning habilitation services.

Adolescent↗

Congenital malformations and consanguinity.

In this study in Bahrain increased maternal age, high parity, consanguinity and a history of 2 or more previous abortions were found to increase the risk of congenital malformation.

Abortion, Spontaneous↗