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Hirschsprung's disease in Oman.

The incidence of Hirschsprung's disease (HD) was studied retrospectively in Oman using hospital-based data. In Oman there is a single pediatric surgery unit where a register has been kept from 1989 to 1994, and because all cases are referred to this unit, a national survey could be carried out. There were 85 children with HD born between 1989 and 1994, and during the period there were 261,000 livebirths among Omani nationals. The population frequency in Oman is 1 in 3,070 (0.3/1,000). Eighty percent of cases presented in the first 6 months. The incidence in different regions and within different tribes of Oman was also studied. The highest frequency (1 in 1,800) is in the North Sharqiya region. There was not a significant seasonal influence in spite of the very high temperatures seen in the desert summer. The ratio of male to female cases was 2.9:1 overall, but less for longer-segment involvement. The consanguinity rate (first and second cousins) was 75%, which is higher than the level of consanguinity in the Omani population. Down's syndrome was observed in nine cases (11%), and a variety of other malformations were seen, including piebaldism, deafness, and HD in two sibships.

Abnormalities, Multiple↗

Lymphocytotoxic antibodies in family members of patients with multiple sclerosis.

Cold-reactive lymphocytotoxic antibodies were found in sera from 14 of 21 (67%) patients with multiple sclerosis. A significantly (p less than 0.01) greater frequency of these antibodies was also demonstrated in patients' household members (12 of 18 [67%]) compared to siblings living elsewhere (3 of 14 [21%]) or normal controls (1 of 13 [8%]). No difference in antibody frequency was found between consanguineous and non-consanguineous family members. These findings suggest that the increase frequency of lymphocytotoxic antibodies in these multiple-sclerosis patients and their family members is an indicator of the presence of a transmissible agent, probably a virus, in many patients with multiple sclerosis.

Adult↗

[Junctional epidermolysis bullosa. Identification of a new mutation in two Lebanese families].

BACKGROUND: Junctional epidermolysis bullosa (JEB) represents a genetically heterozygous group of bullous disorders characterized by dermo-epidermal separation resulting from mutations affecting the main dermo-epidermal adhesion factor, laminin-5, its cellular receptor, integrin alpha6B4, or collagen XVII. We report the identification of a new mutation of LAMA3, encoding laminin-5 alpha3 subunit in two unrelated Lebanese families. PATIENTS AND METHODS: Two female newborn, descending from 1st degree consanguineous marriages, presented a lethal form of EBJ-Herlitz. Histologic, ultrastructural and immunofluorescence studies were performed in order to ascertain the diagnosis and to direct genetic analysis. Mutation search was conducted through direct DNA sequencing of patients and ascendants. RESULTS: Immunohistology of frozen skin samples revealed an extremely reduced immunoreactivity for the alpha3 laminin-5 subunit. The two patients were homozygous carriers (parents heterozygous) of a new missense mutation of LAMA3 gene (exon 32: 4300 insA) encoding the alpha3 subunit of laminin-5. Resulting messenger RNA, rapidly degraded, induced an extremely reduced synthesis of alpha3-polypeptide, truncated in its Cterminal domain. DISCUSSION: LAMB3 gene recurrent mutations R636X and R42X account for about 50p. 100 of EBJ cases affecting Caucasians while mutation Q1083X, affecting the same gene, is recurrent in Arab populations. The newly identified mutation results in extremely reduced synthesis of alpha3 chain and truncation of its C-terminal domain, which is crucial for the intermolecular interactions of laminin-5. Our data are in accordance with recent reports suggesting geographical specificity of EBJ mutations linked to founder effects which are amplified by consanguineous marriages in genetically isolated populations. Otherwise, the observation of other unexplored cases of bullous dermatoses with early demise originating from the same region of the two families herein reported highlights the need for the implementation of a prenatal and postnatal diagnostic strategy regarding these genodermatoses. These studies should target LAMA3 and other genes involved in JEB too.

Consanguinity↗

Chédiak-Higashi syndrome in a Venezuelan black child.

One case of Chédiak-Higashi syndrome (CHS) in a black male child, born to a consanguineous couple from a rural village in the State of Falcón, is described. At birth the child had marked skin depigmentation and ash-gray hair. A few months later he developed an almost normal black skin color. The diagnosis of CHS was established by the presence of large peroxidase-positive granules in his leukocytes. Neutrophils showed decreased chemotaxis and lack of digestive capacity against Candida albicans. Unusual features included extreme rarity of CHS in blacks, progressive repigmentation of the skin, and an early benign evolution. A high consanguinity index in the village from which this patient originated raised the possibility of the presence of a new cluster of this disease in Venezuela.

Black or African American↗

Passage to India: the search for genes causing autosomal recessive nonsyndromic hearing loss.

Hereditary hearing impairment affects approximately 0.05% of all children born in the United States. It is most commonly autosomal recessive, nonsyndromic, and monogenic [autosomal recessive nonsyndromic hearing loss (ARNSHL)]. Although the number of disease loci is not known, some estimates exceed 100. Using a strategy of homozygosity mapping to localize ARNSHL genes by screening consanguineous families for chromosomal regions that are homozygous by descent, we have mapped several genes in multiplex, nuclear, consanguineous families in Tamil Nadu, India. From the mean frequency of the ARNSHL genes in this population, the total number of disease genes is estimated to be 57.

Chromosome Mapping↗

A reconsideration of the factors affecting birth outcome in Pakistani Muslim families in Britain.

Over recent years, Bradford has had a consistently high perinatal mortality rate (PNMR), especially amongst its Asian population, 66% of whom originate from Pakistan. There is a high incidence of consanguineous marriages reported among Pakistani and Muslim couples. Often, this observation is used to explain their higher PNMR and congenital malformation rates. The factors affecting birth outcome in Pakistani women are complex and interrelated. Socioeconomic, genetic, biological and environmental factors all contribute to adverse birth outcome. In addition, these are complicated by discrimination, communication barriers and culture blaming. The aim of this paper is to challenge midwives and other health professionals to reconsider the overwhelming emphasis placed on consanguinity as a factor affecting birth outcome, and to recognise the impact and interplay of other confounding variables.

Confounding Factors, Epidemiologic↗

[Primary immunodeficiency in Tunisia: study of 152 cases].

BACKGROUND: Primary immunodeficiencies are rare immunopathological disorders. A multidisciplinary study group was set up in Tunis in 1988 and has since identified 152 cases of such diseases. We herein present our series and compare it to the international registries. POPULATION AND METHODS: Over a period of 8 years (April 1988-April 1996), 295 children suffering from recurrent infections were investigated; primary immunodeficiency was confirmed in 152 out of them. The immunological investigation included a study of specific and/or non specific humoral and cellular immunity. RESULTS: These 152 patients belonged to 129 families among which 70 were consanguine (54%). Familial primary immunodeficiency occurred in 23 of them. In 39 families (30%), one or more deaths occurred during early childhood. In more than half of the cases (89 cases), the immunological investigations revealed a cellular or combined immunodeficiency with a majority of ataxia-telangiectasia syndromes (53 cases), T cell activation immunodeficiencies (12 cases) and HLA class II deficiency (nine cases). A predominant antibody defect was observed in 35 patients with a majority of agammaglobulinemia (11 cases) and hyper-IgM syndromes (11 cases). A defect of non specific cellular immunity was found in 18 cases (11.8%) including seven cases of chronic granulomatous disease and five cases of leukocyte adhesion deficiency. Three children (1.9%) were deficient in the complement system. Deaths occurred so far in 37 patients (24.3%). CONCLUSIONS: Primary immunodeficiencies are relatively frequent in Tunisia, probably because of the high rate of consanguinity among the general population. The distribution of the different groups of primary immunodeficiencies is characterized by high frequency of ataxia-telangiectasia and hyper-IgM syndrome and scarcity of severe combined immunodeficiencies and Wiskott-Aldrich syndrome.

Child↗

Determinants of infant and child mortality in the West Bank and Gaza Strip.

Infant and child mortality in the West Bank and Gaza Strip has steadily reduced since 1967, even though fertility has remained extremely high. In this paper the determinants of infant and child mortality are discussed, with particular emphasis on the role of consanguineous marriages, short birth spacing and maternal education. It is shown that short birth spacings and type of marriage are more important determinants of infant mortality than maternal education. Moreover, the relative role of consanguineous marriages appears to increase with time.

Adolescent↗

Inbreeding in Ojeda and Pernia, 1875-1985, province of Palencia, Spain.

The degree of isolation was assessed in two contrasting regions in Northern Palencia, Spain, one mountainous with small villages in the valleys (Pernia), the other lower and more open (Ojeda), with corresponding differences in economy. Using data from the parish and diocesan records, the frequencies of consanguineous marriages were calculated from the dispensation data, and the evolution of inbreeding compared. The more isolated region shows a greater degree of inbreeding, though not as high as in some other parts of Spain. Both regions show a decline in inbreeding with time, though in neither did the results indicate that geographic isolation was very outstanding. The most frequent types of consanguineous unions occur between second cousins.

Consanguinity↗

Early marriage among rural and urban females of south India.

Data on 2972 marriages in rural areas and 1180 marriages in urban areas of North Arcot Ambedkar district of South India, during 1982-88, were analysed. The mean age at marriage of females was 18.6 in the rural and 19.6 in the urban area. The proportion of females married before attaining the legal age of 18 years was higher among the rural community (36.8%) than in the urban community (28.9%). Univariate analysis revealed an association between early age at marriage and the socioeconomic variables religion, caste, consanguinity, marital distance, spousal age difference, education and occupation of both bride and bridegroom, and socioeconomic status of the family. Multivariate analysis showed an independent relationship of marital distance and bridegroom's occupation with early age at marriage of females in the rural area alone and the bridegroom's education in the urban area alone. Consanguinity, spousal age difference and bride's education were found to be independently related with early age at marriage of females in both rural and urban areas.

Adolescent↗

Marital structure of the Italian community of Boston, Massachusetts, 1880-1920.

The marital structure of Italians living in Boston, Massachusetts, in the period 1880-1920 was studied in order to explore the integration process in the urban context. The study analyses endogamy and inbreeding, using data on 15,579 marriages from the parish books of the three Italian parishes of Boston. Endogamic rates are very high and increased in time, ranging from 93.9% to 97.3%. This correlated with the growth of the Italian community and the decline of the biased sex ratio. One parish, Our Lady of Pompeii in the South End, displays lower endogamic rates because of the reduced and scattered population attending it. The rate of consanguineous (2.33%) and isonymous (6.38%) marriages, and the coefficients of inbreeding, alpha (0.98 x 10(-3)) and Ft (0.0159), are similar to those of north Italian populations, and lower than those for south and insular Italy. The parish of Our Lady of Pompeii shows consistently higher values than the other two parishes. Marriages between first and second cousins are the main cause of the above values in each parish. Consanguineous marriages and inbreeding increased over time, from the 1890s, and this is in general agreement, although slightly delayed, with the Italian trend.

Acculturation↗

The prevalence and pattern of congenital anomalies of the urinary tract detected by intravenous urography in Kuwait.

We conducted a prospective population-based study in Kuwait to determine the prevalence and pattern of previously undiagnosed congenital anomalies of urinary tract in patients undergoing intravenous urography (IVU) and to examine the demographic factors associated with these anomalies. The study included 2398 consecutive patients undergoing IVU, for various indications, in all the six public hospitals in Kuwait, during the period 1 June 1999-30 September 2000. Patients were also interviewed to obtain selected demographic information. Multiple logistic regression was used to identify factors associated with the anomalies. The average age (+/- SD) of the patients (1623 males, 775 females) was 39.2 +/- 15.1 years. A total of 335 anomalies (12.1% in males, 17.9% in females; p < 0.001) were detected in 300 (12.5%) patients (10.9% males, 15.9% females; p < 0.01). About half (47.2%) of the anomalies involved the kidney, 28.4% renal pelvis, 22.4% ureters, and 2.1% bladder. Multiple regression analysis showed that age < 20 years (odds ratio (OR) = 12.5; 95% confidence interval (95% CI): 7.0-22.3) female gender (OR = 1.5; 95% CI: 1.2-2.0) Kuwaiti nationality (OR = 1.7; 95% CI: 1.2-2.3) and family history of congenital malformation (OR = 3.8; 95% CI: 2.2-6.6) were independently associated with the anomalies of the urinary tract. Overall, 42% of the patients reported a consanguineous marriage between their parents. The frequency of anomalies was higher in individuals who had consanguineous parents (13.8 vs. 11.6%; OR = 1.2) but this positive association did not reach statistical significance. Considering the relatively high prevalence of previously undiagnosed congenital anomalies of the urinary tract, it is important to establish clinical guidelines for early detection and management of these conditions to decrease the associated morbidity and mortality.

Adult↗

Facial clefting in an Arab town in Israel.

To study the prevalence of cleft palate and cleft lip with or without cleft palate in an Israeli Arab town, questionnaires were sent to the parents of 1375 pupils in grades 1 and 2 in all seven primary schools in the town of Taibe, and 1281 responded. The information requested included data about siblings and members of the parental generation to give a total of 16 174, and the presence of consanguinity and history of exposure to medication, radiation, smoking or alcohol during pregnancy. There were four affected individuals among the index cases, of whom two had cleft palate only and two cleft lip with cleft palate, giving prevalence rates for each of these of 1.56/1000. Adding to these the number of affected siblings gave a total of 10 affected individuals; two with cleft palate only (0.39/1000) and eight with cleft lip with or without cleft palate (1.56/1000). Among the parental generation, of 16 reported affected individuals, two had cleft palate only (0.18/1000) and 14 cleft lip with or without cleft palate (1.26/1000). The overall prevalence rate for all 26 affected individuals was 1.6/1000; four of these had cleft palate only (0.24/1000) and 22 had cleft lip with or without cleft palate (1.36/1000). There were no cases whose mothers had been exposed to medication, radiation, smoking or alcohol during pregnancy. The effect of consanguinity was not significant (P < 0.92). This study shows that the prevalence of facial clefting in an Israeli Arab community is consistent with that in the general population worldwide.

Adolescent↗

The gene mutated in adult-onset type II citrullinaemia encodes a putative mitochondrial carrier protein.

Citrullinaemia (CTLN) is an autosomal recessive disease caused by deficiency of argininosuccinate synthetase (ASS). Adult-onset type II citrullinaemia (CTLN2) is characterized by a liver-specific ASS deficiency with no abnormalities in hepatic ASS mRNA or the gene ASS (refs 1-17). CTLN2 patients (1/100,000 in Japan) suffer from a disturbance of consciousness and coma, and most die with cerebral edema within a few years of onset. CTLN2 differs from classical citrullinaemia (CTLN1, OMIM 215700) in that CTLN1 is neonatal or infantile in onset, with ASS enzyme defects (in all tissues) arising due to mutations in ASS on chromosome 9q34 (refs 18-21). We collected 118 CTLN2 families, and localized the CTLN2 locus to chromosome 7q21.3 by homozygosity mapping analysis of individuals from 18 consanguineous unions. Using positional cloning we identified a novel gene, SLC25A13, and found five different DNA sequence alterations that account for mutations in all consanguineous patients examined. SLC25A13 encodes a 3.4-kb transcript expressed most abundantly in liver. The protein encoded by SLC25A13, named citrin, is bipartite in structure, containing a mitochondrial carrier motif and four EF-hand domains, suggesting it is a calcium-dependent mitochondrial solute transporter with a role in urea cycle function.

Adult↗

Childhood blindness in the West Bank and Gaza Strip: prevalence, aetiology and hereditary factors.

A study of all the schools for the blind in the West Bank and Gaza Strip was undertaken during 1991-2. Two hundred and five children had a complete ophthalmic examination. This represented 94% of all children aged 5-15 years attending schools for the blind. According to WHO categories of visual loss, 63% were blind and 21% had severe visual impairment. The main causes of blindness and severe visual loss were retinal (52%), optic atrophy (12%), glaucoma (9%) and cataract (7%). Common retinal diseases included degenerative myopia, Leber's congenital amaurosis, cone dystrophy and retinitis pigmentosa. Depending on the locality, 44-85% of these children were the product of a consanguineous marriage and a positive family history was present in 57%. The minimum prevalence of childhood blindness was estimated to be 0.32/1000 children. A reduction in the prevalence of blindness requires a reduction in consanguineous marriages, genetic counselling for affected families and public health measures to ensure early referral for management of cataract and glaucoma.

Adolescent↗

The gene for pycnodysostosis maps to human chromosome 1cen-q21.

Pycnodysostosis (OMIM 265800) is an autosomal recessive skeletal disorder first described by Maroteaux and Lamy that is characterized by short stature, increased bone density, delayed closure of cranial sutures, loss of the mandibular angle, dysplastic clavicles, dissolution of the terminal phalanges of the hands and feet, dental abnormalities and increased bone fragility. Patients have a typical appearance secondary to prominence of the calvarium, smallness of the facial features, prominent nose and micrognathia. The French painter, Henri de Toulouse Lautrec (1864-1901), is believed to have had the disorder. Although more than 100 cases have been reported, we are aware of only two large consanguinous pedigrees in which the pycnodysostosis disorder segregates. We have studied the segregation of the pycnodysostosis phenotype in a large consanguinous Mexican pedigree, the clinical features of which are very similar to those described in the Arab pedigree studied by Edelson et al. Here, we report linkage for the pycnodysostosis phenotype in the 1cen-q21 region of human chromosome 1, and discuss candidate genes for this skeletal disorder.

Base Sequence↗

Giant axonal neuropathy locus refinement to a < 590 kb critical interval.

Giant axonal neuropathy (GAN) is a rare autosomal recessive neurodegenerative disorder, characterised clinically by the development of chronic distal polyneuropathy during childhood, mental retardation, kinky or curly hair, skeletal abnormalities and, ultrastructurally, by axons in the central and peripheral nervous systems distended by masses of tightly woven neurofilaments. We recently localised the GAN locus in 16q24.1 to a 5-cM interval between the D16S507 and D16S511 markers by homozygosity mapping in three consanguineous Tunisian families. We have now established a contig-based physical map of the region comprising YACs and BACs where we have placed four genes, ten ESTs, three STSs and two additional microsatellite markers, and where we have identified six new SSCP polymorphisms and six new microsatellite markers. Using these markers, we have refined the position of our previous flanking recombinants. We also identified a shared haplotype between two Tunisian families and a small region of homozygosity in a Turkish family with distant consanguinity, both suggesting the occurrence of historic recombinations and supporting the conclusions based on the phase-known recombinations. Taken together, these results allow us to establish a transcription map of the region, and to narrow down the GAN position to a < 590 kb critical interval, an important step toward the identification of the defective gene.

Axons↗

Homozygosity mapping of spinocerebellar ataxia with cerebellar atrophy and peripheral neuropathy to 9q33-34, and with hearing impairment and optic atrophy to 6p21-23.

With the availability of a simple molecular test that distinguishes Friedreich ataxia, the most frequent form of inherited ataxia, from other recessive ataxias, it now becomes possible to unravel the genetic heterogeneity of the latter. We have now localised two genes causing autosomal recessive spinocerebellar ataxia in two consanguineous families. In the first family, the four affected Japanese sibs had spinocerebellar ataxia associated with elevated levels of serum creatine kinase, gamma-globulin, and alpha-foetoprotein. Homozygosity over a 20 cM region allowed to demonstrate linkage at 9q33.3-34.3 with a lod score of 3.0. Genotyping two unrelated Japanese patients from first degree consanguineous parents revealed that one was homozygous for the same region but did not share the biochemical features. In the second family, an Israeli uncle and a niece were affected by an early-onset recessive ataxia and subsequently developed hearing impairment and optic atrophy. Homozygosity over a 17 cM region allowed demonstration of linkage at 6p21-23 with a lod score of 3.25. These two localisations of autosomal recessive ataxia genes represent a first step toward the identification of genetically homogenous, non-Friedreich, ataxic patients and subsequent cloning of the genes.

Chromosome Mapping↗