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International audience; Aims : The objective of our study was to compare the microbiota diversity between two different age groups of Western European women. Methods and Results : Skin‐swab samples were collected directly on the forehead of 34 healthy Western European women: 17 younger (21‐31 years old) and 17 older individuals (54‐69 years old). Bacterial communities were evaluated using the 16S rRNA gene sequencing. Data revealed a higher alpha diversity on the skin of older individuals compared with younger ones. Overall microbiota structure was different between the two age groups, as demonstrated by beta diversity analysis, which also highlighted a high interpersonal variation within older individuals. Furthermore, taxonomic composition analysis showed both an increase in Proteobacteria and a decrease in Actinobacteria on the older skin. At the genus level, older skin exhibited a significant increase in Corynebacterium and a decrease in Propionibacterium relative abundance. Conclusions : Our study revealed a shift in the distribution of skin microbiota during chronological aging in Western European women. Significance and Impact of Study: Altogether these results could become the basis to develop new approaches aiming to rebalance the skin microbiota, which is modified during the aging process.

Infants with limb reduction deficiencies (LRD) often have other associated congenital anomalies. The purpose of this investigation was to assess the prevalence and the types of associated anomalies in a defined population. The associated anomalies in infants with LRD were collected in all livebirths, stillbirths and terminations of pregnancy during 29 years in 387,067 consecutive births in the area covered by our population-based registry of congenital malformations. Of the 317 infants bom with LRD during this period, representing a prevalence of 8.2 per 10,000, 59.9% had associated anomalies. There were 27 (8.5%) cases with chromosomal abnormalities including 17 trisomies 18, and 73 (23.0%) nonchromosomal recognized dysmorphic conditions including 19 VA(C)TER(L) association and 15 Poland syndrome. However, numerous other recognized dysmorphic conditions were registered. Ninety (28.4%) of the cases had multiple congenital anomalies (MCA). Anomalies in the musculoskeletal, the cardiac, the urogenital, and the central nervous system were the most common other anomalies. This study included special strengths: each affected child was examined by a geneticist, all elective terminations were ascertained, and the surveillance for anomalies was continued until 2 years of age. Therefore the overall prevalence of associated anomalies, which was more than one in two infants, emphasizes the need for a thorough investigation of infants with LRD. A routine screening for other anomalies especially in the musculoskeletal system, the cardiovascular system, the urogenital system, the central nervous system, and the digestive system may be considered in infants and in fetuses with LRD.

Articles free to read on publisher website Hereditary haemochromatosis (HHC) is an autosomal recessive disorder of iron metabolism common in populations of north-west European ancestry. The term haemochromatosis was first used by von Recklinghausen (1889) to describe his post-mortem findings in patients who had died from ‘bronzed diabetes’. The condition was first suggested to be familial by Sheldon (1935), although it was as late as 1975 before the genetic nature of the condition was proven, when Simon et al (1975 ) demonstrated association with the HLA-A3 allele in the major histocompatibility complex (MHC) on chromosome 6...

Cases with congenital diaphragmatic hernia (CDH) often have other associated anomalies. The purpose of this investigation was to assess the prevalence and the types of associated anomalies in CDH in a defined population. The anomalies associated with CDH were collected in all live births, stillbirths and terminations of pregnancy during 29 years in 386,088 consecutive pregnancies of known outcome in the area covered by our population based registry of congenital anomalies. Of the 139 cases with CDH born during this period (total prevalence of 3.60 per 10,000), 85 (61.2%) had associated major anomalies. There were 25 (18.0%) cases with chromosomal abnormalities including 12 trisomies 18, and 24 (17.3%) nonchromosomal recognized dysmorphic conditions. There were no predominant recognized dysmorphic conditions, but Fryns syndrome. However, other recognized dysmorphic conditions were registered including fetal alcohol syndrome, de Lange syndrome, sequences (laterality sequence and ectopia cordis), and complexes (limb body wall complex). Thirty six (25.9%) of the cases had non syndromic multiple congenital anomalies (MCA). Anomalies of the cardiovascular system (n = 53, 27.5%), the urogenital system (n = 34, 17.6%), the musculoskeletal system (n = 29, 15.0%), and the central nervous system (n = 19, 9.8%) were the most common other congenital anomalies. We observed specific patterns of anomalies associated with CDH which emphasizes the need to evaluate all patients with CDH for possible associated malformations. In conclusion the overall prevalence of associated anomalies, which was close to two in three infants, emphasizes the need for a thorough investigation of cases with CDH. A routine screening for other anomalies may be considered in infants and in fetuses with CDH. One should be aware that the anomalies associated with CDH can be classified into a recognizable anomaly, syndrome or pattern in more than one out of two cases with CDH.

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Two sisters affected with the same disorder are described. They had webbing of the neck, the antecubital fossae and the popliteal regions, together with flexion deformities of the limb joints and anomalies of the vertebrae. Eight other cases are known. The condition is inherited in an autosomal recessive mode.

Here, we summarize the contributions to group 16 of Genetic Analysis Workshop 15, held in Florida, U.S.A. The theme of this group was preprocessing of expression quantitative trait loci (eQTL) studies using the Affymetrix platform. The objective of the Genetic Analysis Workshop 15 problem 1 dataset was to use transcript levels that are measured using DNA microarrays as quantitative traits and localize the genes or other features of the DNA that control gene expression by quantitative trait loci linkage analyses. All contributors of this group used the microarray expression profiles (problem 1) data. Various approaches and questions were examined to investigate the effects of preprocessing methods and/or gene filtering on the interpretation of data, specifically on heritability estimates of gene expression and on linkage results. In addition, some contributors focused on the statistical issues involved in large-scale genetic analyses of quantitative traits that account for or build composite phenotypes from a large number of correlated traits. Since the true eQTLs are not known in the problem 1 data, results from the 11 studies cannot be fully evaluated for the methods employed. However, several common trends were found. All reports concluded that preprocessing statistical analyses may have an important impact on eQTL analyses and on the identification of cis-/trans-regulators and/or major biological pathways. Genet. Epidemiol. 31(Suppl. 1):S132–S138, 2007. © 2007 Wiley-Liss, Inc.

Summary Background Atopic dermatitis (AD) is a chronic inflammatory skin disease in which skin barrier function is disrupted. In this AD environment, proinflammatory cytokines are upregulated, promoting a vicious circle of inflammation. Although several three-dimensional in vitro models mimicking AD have been published, no study has presented a fully characterized and controlled model of AD-related inflammation. Objectives To develop and characterize, from the morphological to the molecular level, a compromised reconstructed epidermis (RE) mimicking AD-related inflammation in vitro. Methods Normal human keratinocytes were used to generate RE, treated or not with an inflammatory cocktail (polyinosinic–polycytidylic acid, tumour necrosis factor-α, interleukin-4 and interleukin-13). Results The inflammatory cocktail induces some modifications observed in patients with AD: (i) it leads to spongiosis; (ii) it alters early and terminal differentiation proteins; (iii) it increases thymic stromal lymphopoietin and interleukin-8 secretion by keratinocytes and (iv) it results in a specific gene expression pattern. Conclusions The inflammatory context contributes to the morphological, functional and transcriptomic changes observed in AD skin. As a result, this compromised RE model shares some characteristics with those found in AD skin and thus can be used as a relevant tool for screening formulations and drugs for the treatment of AD.

Keratoconus (KC; MIM 148300) is a non-inflammatory corneal thinning disorder. Progressive thinning and protrusion of the cornea lead to loss of visual acuity for which the only effective treatment is corneal transplantation. The estimated prevalence of KC is 1–4 per 2000 in the general population.1 The age of onset is often at puberty, and the disorder is progressive until the third or fourth decade of life when it usually arrests. KC is a major cause of corneal transplantation in developed countries. The cause of KC is still unknown. Histological observations have demonstrated degradation of the corneal epithelium basal membrane, diminution of the number of collagen fibrils, thinning of the corneal stroma, and keratocyte apoptosis.2,3 Biochemical studies describe increased activity of metalloproteinases (MMP-2 and MMP-9) and lower expression of protease inhibitors such as α1-protease inhibitor.4,5 Sporadic KC is the most common presentation; however, a positive familial history has been reported in at least 6–10% of patients.1 Twin studies performed since the advent of modern computerised videokeratoscopy have reported four monozygotic pairs concordant for KC and two monozygotic pairs which were discordant,6–9 suggesting a genetic component for KC. Keratoconus prevalence in first degree relatives of KC patients is significantly higher than in the general population, demonstrating familial aggregation of the trait.10,11 Most published studies have suggested autosomal dominant inheritance of KC with incomplete penetrance or variable expression.1,12 Autosomal recessive inheritance as well as rare cases of X linked inheritance have also been described.10,13 In some rare cases, KC is associated with other genetic disorders such as trisomy 21, atopy, and Leber congenital amaurosis.14,15 KC gene localisation efforts to date have been carried out in rare large families or in population isolates where genetic heterogeneity is minimised. …

Multiple sclerosis (MS) is a demyelinating autoimmune disease with a strong yet complex genetic component. To date only the HLA-DR locus, and specifically the HLA-DR15 allele, has been identified and confirmed as influencing the risk of developing MS. Genomic screens on several datasets have been performed and have identified several chromosomal regions with interesting results, but none have yet been confirmed. We tested seven of the most-promising regions (on chromosomes 1p, 2p, 3p, 3q, 5q, 19q, and Xp) identified from several genomic screens in a dataset of 98 multiplex MS families from the United States and 90 multiplex MS families from France. The results did not confirm linkage to 2p, 3q, 5q, or Xp in the overall dataset, or in subsets defined by geographic origin or HLA-DR15 status. Regions on 1p34, 3p14, and 19q13 produced lod scores >0.90 in at least one subset of the data, suggesting that these regions should be examined in more detail.

Background: Although much progress has been made recently in characterising the proteins involved in duodenal iron trafficking, regulation of intestinal iron transport remains poorly understood. It is not known whether the level of mRNA expression of these recently described molecules is genetically regulated. This is of particular interest however as genetic factors are likely to determine differences in iron status among mouse strains and probably also contribute to the phenotypic variability seen with disruption of the haemochromatosis gene. Aims: To investigate this issue, we examined concomitant variations in duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferroportin 1 (FPN1), hephaestin, stimulator of Fe transport (SFT), HFE, and transferrin receptor 1 (TfR1) transcripts in response to different dietary iron contents in the four mouse strains C57BL/6, DBA/2, CBA, and 129/Sv. Subjects: Six mice of each strain were fed normal levels of dietary iron, six were subjected to the same diet supplemented with 2% carbonyl iron, and six were fed an iron deficient diet. Methods: Quantification of mRNAs isolated from the duodenum was performed using real time reverse transcription-polymerase chain reaction. Results: There was a significant increase in mRNA expression of Dcytb, DMT1, FPN1, and TfR1 when mice were fed an iron deficient diet, and a significant decrease in mRNA expression of these molecules when mice were fed an iron supplemented diet. Strain to strain differences were observed not only in serum transferrin saturations, with C57BL/6 mice having the lowest values, but also in hepatic iron stores and in duodenal mRNA expression of Dcytb, DMT1, FPN1, hephaestin, HFE, and TfR1. Conclusions: The results favour some degree of genetic control of mRNA levels of these molecules.

Background & Aims: Hfe knockout mice, like patients with hereditary hemochromatosis, have augmented duodenal iron absorption and increased iron deposition in hepatic parenchymal cells. The goals of the present study were to gain further insight into the control of iron absorption by comparing the transcript levels of iron-related genes in the duodenum of DBA/2 Hfe −/− mice, susceptible to iron loading, and wild-type controls, and to test whether variations in the duodenal expression of these messengers contribute to the DBA/2 and C57BL/6 strain differences in the severity of hepatic iron loading. Methods: Expression of the different transcripts was quantified by real-time polymerase chain reaction. Results: The 2 strains differ strikingly, not only in the severity of hepatic iron loading, but also in the duodenal expression of iron-related genes. In DBA/2 Hfe −/− mice, increased intestinal iron absorption results from the concomitant up-regulation of the Dcytb, DMT1, and FPN1 messengers. No increase in the expression of these messengers is seen in C57BL/6 Hfe −/− mice. Conclusions: The up-regulation of these transcripts suggests that an inappropriate iron-deficiency signal is sensed by the duodenal enterocytes, leading to an enhanced ferric reductase activity and the increase of duodenal iron uptake and transfer to the circulation. The genes modifying the hemochromatosis phenotype probably act by modifying the expression of these 3 messengers. GASTROENTEROLOGY 2002;122:745-751

Objectives: To provide data on oligohydramnios associated with congenital anomalies in 225,669 consecutive pregnancies. Material and Methods: The malformations in this study came from births of known outcome recorded in our registry of congenital malformations. Routine ultrasonographic examination was performed. Diagnosis of oligohydramnios was made ultrasonographically. For each case, a control was chosen. Results: The prevalence of this association was 0.99 per thousand (224 cases). A case-control study allowed the examination of genetic and environmental factors for the origin of oligohydramnios associated with congenital malformations. Diagnosis of oligohydramnios associated with congenital malformations was made prenatally in 32.6% of the cases; 12.0% of the infants were stillborn. Fifty-nine percent of the cases had more than one malformation, 13.8% had a chromosomal aberration, and 27.6% had multiple malformations that do not constitute a syndrome. The more frequent malformations associated with oligohydramnios were urinary, musculoskeletal, digestive and cardiac. There was increased parental consanguinity. The frequency of oligohydramnios and congenital anomalies among first-degree relatives was 4.5% and first-degree relatives had more malformations than controls (8.0 vs. 3.1%, p < 0.05). Threatened abortions and diabetes mellitus were significantly more frequent among mothers of the children with congenital malformations associated with oligohydramnios than among the controls. Conclusions: Our study demonstrated that careful fetal examination has to be performed when oligohydramnios is diagnosed as congenital malformations are often associated with oligohydramnios. We recommend the use of fetal chromosome analysis and careful ultrasonographic examination in every pregnancy complicated by oligohydramnios.

Genes that predispose to haemochromatosis are though to be located within the several megabases telomeric of HLA-A. Further recombinant mapping has been used previously to map susceptibility genes for diseases such as insulin-dependent diabetes mellitus, myasthenia gravis and cystic fibrosis, and should be useful in relation to haemochromatosis. However, this method requires the recognition of ancestral haplotypes within the susceptibility region. Using a panel of six microsatellite markers from this region (MOG A, MOG B, MOG C, D6S464, D6S306 and D6S105), we show that ancestral haplotypes extend telomeric of HLA-A, at least as far as D6S105. Nine of 14 haplotypes carrying HLA-B7 and HLA-A3 shared the same microsatellite alleles between HLA-A and at least D6S105. Similarly, nine of 10 haplotypes sharing HLA-B8 and HLA-A1 shared the same microsatellite alleles, although a different set to those with HLA-B7 and HLA-A3. Haplotypes representing historical recombination events were also identified. These two findings demonstrate that recombinant mapping may be applicable to the mapping of disease genes in this region.

A Celtic origin for hemochromatosis, a common genetic iron metabolism disorder, has been postulated for a long time. To check whether the two mutations recently identified in the HLA-class I candidate gene for this disease were found only in Caucasians, we examined their frequencies in individuals originating from Algeria, Ethiopia, and Senegal. The presumably disease-causing mutation, responsible for the Cys282Tyr substitution, was not found in any member of these ethnic groups, although it was shown to be highly prevalent in populations of European ancestry. This geographic distribution supports the previously suggested Celtic origin for the disease. In contrast, the mutation responsible for the His63Asp substitution is not restricted to European populations. Although absent in the Senegalese, it was found on about 9% of the chromosomes of the Central Ethiopians and Algerians (Mzab) genotyped for this study. This second mutation, which probably represents a common variant unrelated to hemochromatosis, thus appears to have occurred earlier than that responsible for the Cys282Tyr substitution. More detailed population studies are needed to provide information on the age of these two mutations and eventually show how the hemochromatosis-causing mutation chronologically spread throughout Europe.

Analysis of 784 informative meioses in the CEPH pedigrees revealed a total of 22 recombination events having occurred in the 6-Mb region between D6S265 (70 kb centromeric of HLA-A) and D6S276. These 22 breakpoints were localized with respect to anonymous polymorphic markers, leading to a detailed genetic map of the region telomeric to the human major histocompatibility complex. A nonrandom pattern of recombination was observed throughout this region: the low recombination rate of 0.19% within the 4-Mb interval centromeric to the HLA class I-like candidate gene for hemochromatosis indeed contrasts with the approximate 1% rate observed within the most telomeric two megabases. This reduced rate of recombination may be due to selective constraints depending on environmental factors related to immunity and iron status or to structural variations hampering proper meiotic pairing of homologous sequences. Population data from other human genome segments are now needed to determine whether linkage disequilibrium extending over 4 Mb is unique to this region.

In their Perspective “The future of genetic studies of complex human diseases ([13 Sept., p. 1516][1]), Neil Risch and Kathleen Merikangas emphasize that such studies might benefit greatly from approaches based on gametic disequilibrium. Recent genome scans ([1][2]) and our own data on human

Infants with radial ray deficiencies very often have other associated congenital anomalies. The reported frequency and types of associated malformations vary between different studies. The purpose of this investigation was to assess the frequency and types of associated malformations among infants with radial ray deficiencies in a geographically well-defined population from 1979 to 2004 of 346,831 consecutive births. Of the 73 infants with radial ray deficiencies born during this period (prevalence at birth of 2.1 per 10,000), 75% had associated malformations. Infants with associated malformation were divided into recognizable conditions (16 (22%) infants with chromosomal and 20 (27%) with non chromosomal conditions), and non recognizable conditions (19 (26%) infants with multiple malformations). Trisomies 18 and autosomal deletions were the most frequent chromosomal abnormalities. VACTERL association, thrombocytopenia absent radii syndrome, Fanconi anemia and Holt-Oram syndrome were most often present in recognizable non chromosomal conditions. Malformations in the musculoskeletal, cardiovascular and urogenital systems were the most common other anomalies in infants with multiple malformations and non recognizable conditions. The frequency of associated malformations in infants with radial ray deficiencies emphasizes the need for a thorough investigation of these infants. Routine screening for other malformations especially musculoskeletal, cardiac and urogenital systems anomalies may need to be considered in infants with radial ray deficiencies, and referral of these infants for genetic evaluation and counseling seems warranted.

The etiology of congenital diaphragmatic hernia (CDH) is unclear and its pathogenesis is controversial. Because previous reports have inconsistently noted the type and frequency of malformations associated with CDH, we assessed these associated malformations ascertained between 1979 and 2003 in 334,262 consecutive births. Of the 115 patients with the most common type of CDH, the posterolateral, or Bochdalek-type hernia, 70 (60.8%) had associated malformations. These included: chromosomal abnormalities (n = 21, 30.0%); non-chromosomal syndromes (Fryns syndrome, fetal alcohol syndrome, De Lange syndrome, CHARGE syndrome, Fraser syndrome, Goldenhar syndrome, Smith-Lemli-Opitz syndrome, multiple pterygium syndrome, Noonan syndrome, and spondylocostal dysostosis); malformation sequences (laterality sequence, ectopia cordis); malformation complexes (limb body wall complex) and non syndromic multiple congenital anomalies (MCA) (n = 30, 42.9%). Malformations of the cardiovascular system (n = 42, 27.5%), urogenital system (n = 27, 17.7%), musculoskeletal system (n = 24, 15.7%), and central nervous system (n = 15, 9.8%) were the most common other congenital malformations. We observed specific patterns of malformations associated with CDH which emphasizes the need to evaluate all patients with CDH for possible associated malformations. Geneticists and pediatricians should be aware that the malformations associated with CDH can often be classified into a recognizable malformation syndrome or pattern (57.1%).

The myelin basic protein (MBP) gene is a candidate locus for susceptibility to multiple sclerosis. Several groups have tested a complex (TGGA)n repeat in the 5' region of this gene for association/linkage with multiple sclerosis, with divergent results. This region of tandem repetitive sequence has been subjected to complex rearrangements, and there is a possibility that alleles of the same size have different internal structures, which reduces the interest of this marker for linkage disequilibrium studies and may at least partly explain the conflicting results obtained so far. To overcome this problem, we isolated a new polymorphic (CA)n repeat within the Golli-MBP locus. The limited number of alleles identified makes this other marker suitable for transmission disequilibrium studies. We tested this marker for linkage with multiple sclerosis, using the transmission-disequilibrium test (TDT) on a sample of 196 nuclear families in which the genotypes of both parents could be unambiguously defined. We found no evidence of transmission disequilibrium between multiple sclerosis and any of the three alleles of this marker, even when the patients were subdivided according to their HLA-DRB1*1501 status. The present data thus provide no evidence for a contribution of the MBP gene to multiple sclerosis susceptibility in French patients.

GM and KM immunoglobulin allotypes, which are the markers, respectively, of the constant parts of the heavy and the light chains of the IgG1, IgG2 and IgG3 subclasses, have been analysed in diabetic mellitus patients and controls living in New Caledonia. We tested 40 Europeans, 256 Melanesians and 44 Polynesians, as well as their 340 matched controls, in order to search for a genetic susceptibility at those polymorphic loci. All the subjects were tested for G1M (1, 2, 3, 17), G2M (23), G3M (5, 6, 10, 11, 13, 14, 15, 16, 21, 24, 28) and KM (1) by the classical hemagglutination method. The frequencies of GM haplotypes and KM alleles have been estimated by a maximum likelihood method. The results are in favour of no influence of the GM and KM loci. The prevalence of diabetes mellitus varies in the populations of New Caledonia: Polynesians are at much higher risk than Melanesians or Europeans. The GM haplotype distribution differs among ethnic groups; so they provide a useful marker to measure genetic admixture. The higher prevalence of diabetes observed among New Caledonians of European origin compared to the prevalence in Europe may be explained by genetic admixture with neighbouring Pacific populations, notably Polynesians (Asian haplotypes are present at a frequency of 9.4%). So, the genetic admixture should be measured in any genetic epidemiological study.

Objective Infants with oral clefts (OCs) often have other associated congenital defects. The reported incidence and the types of associated malformations vary between different studies. The purpose of this investigation was to assess the prevalence of associated malformations in a geographically defined population. Method The prevalences at birth of associated malformations in infants with OCs were collected between 1979 and 1996 on all infants born in the area covered by the registry of congenital anomalies of Northeastern France in 238,942 consecutive births. Results Of the 460 cleft infants born during this period, 36.7% had associated malformations. Associated malformations were more frequent in infants who had cleft palate (46.7%) than in infants with cleft lip and palate (36.8%) or infants with isolated cleft lip (13.6%). Malformations in the central nervous system and in the skeletal system were the most common other anomalies, followed by malformations in the urogenital and cardiovascular systems. Weight, length, and head circumference of children with OCs and multiple associated malformations were lower than in controls, as was the weight of the placenta. Prenatal diagnosis was rarely done by fetal ultrasonographic examination in isolated clefts. However, even in multiple associated malformations, prenatal diagnosis by fetal ultrasonographic examination had a low sensitivity, 31.6%. Conclusion The overall prevalence of malformations, which was one in more than three infants, emphasizes the need for a thorough investigation of infants with clefts. A routine screening for other malformations especially skeletal, central nervous system, and cardiac defects may need to be considered in infants with clefts, and genetic counseling seems warranted in most of these complicated cases.

The risk for birth defects in the offspring of first-cousin matings has been estimated to increase sharply compared to non consanguineous marriages. As a general decline in the frequency of consanguineous marriages was observed in this century, one wonders whether consanguinity is still a factor in the appearance of birth defects in developed countries. Based on our registry of congenital anomalies we tried to answer to this question. In the population studied in North-Eastern France a consanguineous mating was known in 1.21% of the cases with congenital anomalies, vs. 0.27% in controls, (p0.001). The frequency of the malformations recorded paralleled the degree of consanguinity: out of 89 malformed children, 51 were seen in first-cousins mating (10.3 times more frequent than in offspring of non consanguineous couples), 17 in second-cousins marriages and 18 in more distant relatives mating. Three were uncle-niece marriage. Excluding known mendelian conditions these numbers were 73, 36, 17 and 17 respectively and the corresponding relative risk were 3.68, 3.01, 3.41 and 4.89 respectively. Therefore there is a negative dose-response effect between level of inbreeding and risk of congenital malformations. Consanguineous mothers were more often pregnant than non consanguineous mothers (p0.01) and they had more stillbirths than non consanguineous mothers. These results show that consanguinity is still a factor of birth defects and they must be taken into account for genetic counseling of inbred marriages, in developed countries.

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune disease of the central nervous system that exhibits many pathologic similarities with multiple sclerosis. The genetic loci that contribute to mononuclear cell infiltration of the central nervous system and clinical manifestations of EAE in the rat were investigated in the F2 progeny of the highly susceptible Lewis and resistant Brown Norway strains. The data confirmed that the Lewis allele of a MHC-linked gene is necessary, but not sufficient, to confer EAE susceptibility in the F2 progeny. Subsequent analyses were thus restricted to the subset of the F2 animals with EAE-predisposing MHC genotypes. A genome-wide scan approach was performed using 103 microsatellite markers covering 85% of the genome. Two non-MHC regions were identified, one near the centromere of chromosome 4 and the other on the long arm of chromosome 10, that significantly contributed to the disease. In addition, three regions on chromosomes 9, 13, and 17 were suggestive for linkage. Congenic mapping is now needed to reduce the support intervals encoding the loci of interest to sizes amenable to physical mapping and to eventually demonstrate the involvement of some of the candidate genes of immunologic importance localized in these regions.

The genetics and the epidemiology of Down syndrome (DS) was studied in the area which is covered by our registry of congenital malformations. For each of the 398 new DS cases which were ascertained during the period 1979 to 1996 more than 50 factors were studied and compared to those from control infants. The prevalence of DS was 1.66 per 1000; 2.2% of the DS cases were stillbirths and 29.4% were induced abortions. Karyotypes were obtained in 391 cases of which all but 23 were 47,+21;9 were mosaics (2.3%), and 14 had translocations (3.6%). Interchromosomal effect was a question in 7 cases. The most common types of associated malformations were cardiac anomalies (46.2%) and intestinal atresias (6.0%). Seasonality or time/space clusters were not observed in spite of the Chernobyl nuclear accident. No paternal age effect was demonstrated; 5.3% of the mothers of DS had 2 previous spontaneous abortions (controls 3.7% p0.05). At birth, the DS infants measured and weighted less and their head circumference was lower than in control infants. Weight of placenta was also lower than in control infants. In this material there were 4.5% of consanguineous marriages (P0.01). The pregnancies of the DS children were more often complicated by threatened abortions than in the controls, 3.2% of the mothers of the DS children were diabetic controls (1.7%), although the difference was not statistically significant. For all other factors studied no statistically significant difference with respect to controls could be demonstrated.

Congenital eye malformations were studied in a small geographical area in 212,479 consecutive births. For each of the 145 new cases studied during the period 1979 to 1994, more than 50 factors were compared in probands and in controls. The prevalence rate of congenital eye malformations was 6.8 per 10,000 for microphthalmia 1.7, anophthalmia 0.23, cataract 2.7 and coloboma 1.4 respectively. Sex ratio was 0.82. Prenatal diagnosis was performed in 18 cases and 7 cases were induced abortions. The more common types of associated malformations in the 81 affected cases (53.8%) with at least one anomaly other than an eye malformation were clubfeet, microcephaly, hydrocephaly, cleft lip/palate and facial dysmorphia. At birth infants with eye malformations and other malformations were smaller, weighted less and their head circumference was lower than in controls. Placental weight was also lower than in controls. Pregnancies with eye malformations were more often complicated by threatened abortion, oligoamnios and polyhydramnios. Mothers of children with congenital eye malformations took more often drugs during pregnancy than mothers of controls. Fathers of children with congenital eye malformations were more often exposed to occupational hazards than fathers of controls. There was a significant association between eye malformations and consanguinity of parents. The recurrence risk for first degree relatives of probands was 8.9%. First degree relatives of probands had more than three times the prevalence of non-eye malformations than controls. These results are of relevance to genetic counseling.

A candidate gene for hemochromatosis has recently been localized on the short arm of chromosome 6, about 4 megabases telomeric to the major histocompatibility complex. It encodes a protein that exhibits significant similarity to the HLA class I molecules and can be provisionally designated HLA-hc. Genotype analysis of 94 hemochromatosis patients living in France and a similar number of controls confirms that the disease is strongly associated with homozygosity at nucleotide 845 (72% of the patients and none of the controls carry two copies of the 845A variant). The data are consistent with hemochromatosis being a heterogeneous disease: about 79% of the cases in this sample would be caused by a defect in HLA-hc and 21% by an unrelated mechanism. A second variant (187 G) enriched on patient chromosomes that do not carry the 845A mutation might influence the affinity of a ligand for HLA-hc; the exact nature of this ligand remains to be discovered. The 845A variant is the best genetic marker for the disease identified to date, and the detection of 845A homozygosity should now permit diagnosis of a readily curable disease and the prevention of sometimes deadly complications in at least 72% of the patients.

Congenital anal atresias were studied in a small geographical area in 225,752 consecutive births. For each of the 108 new cases studied during the period 1979 to 1995, more than 50 factors were compared in probands and in controls. The prevalence rate of congenital anal atresias was 4.8 per 10,000 births. Sex ratio was 0.96. Prenatal diagnosis was performed in 14 cases and 11 cases were induced abortions. The more common types of associated malformations in the 45 non syndromic affected cases with at least one major anomaly other than anal atresia were renal agenesia, genital anomalies and ventricular septal defect. At births infants with anal atresia and other malformations were smaller, weighted less and their head circumference was lower than in controls. Placental weight was also lower than in controls. Pregnancies with anal atresia were more often complicated by threatened abortion, oligoamnios and polyhydramnios. Mothers of children with congenital anal atresia took more often drugs during pregnancy than mothers of controls. Fathers of children with anal atresia were more often exposed to occupational hazards than fathers of controls. There was a significant association between anal atresia and consanguinity of parents (p0.05). The recurrence risk for first degree relatives of probands was 3.7%. First degree relatives of probands had more than twice the prevalence of non-anal atresia malformations than controls.

The objective of this study was to determine in total prevalence of neural tube defects (NTD) in northeastern France during 1979-1994 inclusive, the impact of prenatal diagnosis on birth prevalence. All births and termination of pregnancy affected by NTD were ascertained from multiple sources thank to our registry of congenital anomalies. In our region maternal serum alpha-fetoprotein screening is not available whereas routine ultrasonographic screening of congenital anomalies is performed in all pregnant women. Total prevalence of NTD during 1979-1994 was 10.73 per 10,000 with no upward or downward trend. The total prevalence of NTD in our region remained stable. However birth prevalence fell significantly. The fall was 100 per cent for anencephaly and 60 per cent for spina bifida. This birth prevalence was unchanged for encephalocele. This decrease for anencephaly and spina bifida was obtained by routine ultrasonographic examination only and termination of pregnancy. Comparison with similar studies in other countries demonstrated that screening by maternal serum alpha-fetoprotein is needed in our region.

Prenatal diagnosis performed by fetal ultrasound scan is now a routine part of antenatal care in many countries. That an increasing number of fetal anomalies may be detected on prenatal ultrasound is beyond doubt. However what is theoretically possible is not, always done in practice specially when gastrointestinal atresias (GIA) are concerned and when whole antenatal populations are screened rather than high risk groups. Thanks to our registry of congenital anomalies a retrospective study was undertaken to evaluate the prenatal detection of GIA by ultrasound scan in 118,265 consecutive pregnancies of known outcome. Only 31 out of 129 malformed fetuses with GIA were detected (24.0%). The sensitivity of detection varied from 51.4% for atresia of the small intestine to 24.2% for esophageal atresia and 8.2% for ano-rectal atresia. No isolated case with esophageal atresia and ano-rectal atresia were diagnosed. Our results stress the need to perform scans ator = 18 weeks gestation and to train sonographers in order to improve prenatal detection of GIA.

Polymorphic (CTC)n and (TAAA)n sequences were identified in exons 1 and 8 of the myelin oligodendrocyte glycoprotein (MOG) gene. The different alleles were detected by a method combining fluorescence labeling of polymerase chain reaction (PCR) products and use of an automated DNA sequencer. Although only two alleles differing by the number of leucine residues encoded by the (CTC)n array were detected at the first locus, seven alleles were identified at the second. The high degree of polymorphism (75%) of the tetranucleotide repeat makes this marker informative for association or linkage studies with diseases such as hemochromatosis or multiple sclerosis.

The MOG locus, located on chromosomal bands 6p21.3-p22 and mapped about 100 kb telomeric to HLA-F, was isolated from cosmid ICRFc109A2434 and shown to contain three microsatellites. These CA-repeat polymorphic markers were characterized in a sample of 173 healthy unrelated individuals and 84 DNAs from the HLA Workshop reference panel, by a method combining fluorescence labeling of PCR products and use of an automated DNA sequencer. For the three markers, frequencies of heterozygotes are well predicted from allele frequencies by the Hardy-Weinberg rule, which suggests that problems of allele nonamplification are unlikely. Typing of cell lines homozygous in the HLA region allowed unambiguous definition of 81 HLA-MOG haplotypes and showed that several HLA ancestral haplotypes extended to the MOG region. The high degree of polymorphism (59%, 51%, and 81% at the three loci, respectively, and 87% at the haplotype level) makes these new markers informative for association or linkage studies with diseases such as hemochromatosis or multiple sclerosis, and for studies aimed at precisely delineating the site of crossover in chromosomes in which recombination occurred in the distal part of the HLA class I region.

Prenatal diagnosis performed by ultrasound scan is now a routine part of antenatal care in our region. How many fetal anomalies are actually detected by this procedure? We have used our registry of congenital malformations to answer this question regarding to Internal Urinary System (IUS) anomalies. The mean time of detection of IUS anomalies was 29 weeks of pregnancy (12–39). The sensitivity of prenatal diagnosis of IUS anomalies by ultrasonographic examination was 59.3% for isolated malformations (fetuses with only one anomaly) and 46.0% for multiple malformed children with IUS anomalies. For all cases of IUS anomalies the percentage of prenatal detection was 56.0. Termination of pregnancy was performed in 9.4% of the cases.

The objective of this study was to determine in total prevalence of neural tube defects (NTD) in northeastern France during 1979-1992 inclusive, the impact of prenatal diagnosis on birth prevalence. All births and termination of pregnancy affected by NTD were ascertained from multiple sources thank to our registry of congenital anomalies. In our region maternal serum alpha-fetoprotein screening is not available whereas routine ultrasonographic screening of congenital anomalies is performed in all pregnant women. Total prevalence of NTD during 1979-1992 was 10.94 per 10,000 with no upward or downward trend. The total prevalence of NTD in our region remained stable. However birth prevalence fell significantly. The fall was 100 per cent for anencephaly and 60 and 50 per cent for spina bifida and encephalocele, respectively. This decrease was obtained by routine ultrasonographic examination only and termination of pregnancy. Comparison with similar studies in other countries demonstrated that screening by maternal serum alpha-fetoprotein is needed in our region.

Strategies for studying the genetics of autoimmune diseases have undergone a considerable evolution during the last years, especially due to molecular biology techniques and to systematic genome studies. Genetic factors account for 20 to 40% of the risk, and environmental elements play a major role. The major histocompatibility complex comprising HLA genes remains the immunogenetic system most studied and most closely associated with various autoimmune diseases. These associations are mainly observed with HLA class II genes polymorphisms; the precise knowledge of their structure has allowed to define HLA sequence polymorphisms which are themselves risk markers: specific combinations of HLA-DQA and DQB alleles in insulin-dependent diabetes mellitus or a given DR, DQ haplotype for multiple sclerosis. No strong association with HLA-DP has been demonstrated. In all cases the genes involved have a normal structure and the disease is secondary to the combination of a given set of genes with environmental factors. The present knowledge of insulin-dependent diabetes mellitus and multiple sclerosis genetics is rather advanced. Other genes of the HLA region might also be involved in the genetic susceptibility. Results about other immunogenetic systems (T cell receptor genes or heavy chain immunoglobulin genes) are still contradictory but no major gene for autoimmune susceptibility seems to exist in these regions; however autoimmune diseases are under polygenic control; susceptibility genes shared between different diseases often occurring within the same families (Graves' disease and insulin-dependent diabetes mellitus) and genes specific for a given disease (insulin gene region in diabetes) both exist. The present rapid progress in this area is due to the use of highly polymorphic markers randomly distributed across the genome (microsatellites being most informative) and that of animal models: the list of "candidate genes or regions" potentially involved in the genetics of autoimmune diseases is enlarging; the development of coordinated epidemiological studies of molecular genetics along with the sharing of biological resources between different teams allow to build up powerful informative studies which will confirm or refute those "candidates". However, once the list of genes involved is established their mechanism of action will still take time to elucidate.

In the last decade many reports have confirmed the old assumption of a “genetic susceptibility to multiple sclerosis”. These studies have been investigated in three orientations: → genetic analysis of pedigrees and study of concordance for MS in twins: the main results are a weak genetic susceptibility with a probable multigenic influence. → association studies with candidate genes and linkage analysis in multiplex families: among these genetic markers, the HLA genes are assumed to be of the greatest importance, particularly in Caucasoid patients, the alleles DRB*1501, DQA1* 0102 and DQBl*0602. → by analogy with Experimental Allergic Encephalomyelitis (EAE) molecular genetic studies were undertaken in an attempt to define the functional role of these markers in the pathophysiology of the disease more specifically the immunogenic response of T lymphocytes against Myelin Basic Protein (MBP).

Examination of data from our regional registry of congenital anomalies indicated that 217 children with Down syndrome (DS) were registered (liveborn, stillborn or termination of pregnancy) to mothers living in the Strasbourg area from 1980 to 1992 inclusive. This represents a period prevalence of 1.25 per 1000 total births. From 1980 to 1987, 93 children with DS were registered (prevalence of 0.79 per 1000) whereas from 1988 to 1992, 124 trisomic 21 were identified (prevalence of 1.81 per 1000). In our country since 1980, prenatal diagnosis is offered, free of charge, to all women being 38 years old or more. The percentage of women in whom prenatal diagnosis was performed was "en plateau" since 1986, around 60 per cent. No screening program based on detection of markers in maternal serum (AFP, hCG, U3) is available in our region. A changing pattern of risk in relation to maternal age was identified. In the general population, women under 35 years gave births to 91.7 per cent of all children in 1986 and to 81.1 per cent of all children in 1990. From 1980 to 1987 34.7 per cent of the children with DS were registered in mothers older than 35 years of age, from 1988 to 1992 this percentage was 46.3. From 1982 to 1987, 33 DS were born alive from mothers over 35 years whereas from 1988 to 1992, 25 livebirths DS were born from mothers over 35 years although interruption of DS pregnancies was more frequent in women older than 35 years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

The Jewish population has an increased frequency of inflammatory bowel disease compared with their non-Jewish neighbours. Genetic factors have been implicated in the aetiology of this disorder and may contribute to ethnic differences. This study determined the familial empirical risks for inflammatory bowel disease in the first degree relatives of inflammatory bowel disease probands (for both Jews and non-Jews) for the purpose of accurate genetic counselling and genetic analysis. A total of 527 inflammatory bowel disease patients from Southern California (291 Jews and 236 non-Jews) were questioned about inflammatory bowel disease in their first degree relatives (a total of 2493 individuals). Since inflammatory bowel disease has a variable and late age of onset, age specific incidence data were used to estimate the life time risks and to make valid comparisons between the different groups. In the first degree relatives of non-Jewish probands, the life time risks for inflammatory bowel disease were 5.2% and 1.6% when probands had Crohn's disease and ulcerative colitis respectively. These values were consistently lower than the corresponding risks for relatives of Jewish patients -7.8% and 4.5% for Crohn's disease and ulcerative colitis probands respectively (p value for comparison between Jews and non-Jews: 0.028; between ulcerative colitis and Crohn's disease: 0.005). These data provide the requisite basis for genetic counselling for these disorders in the white American population. In addition, these different empirical risks for relatives of Jewish and non-Jewish probands allow rejection of single Mendelian gene models for inflammatory bowel disease, but are consistent with several alternative genetic models.

Risk factors were studied in 123 children with limb reduction defects (LRD) from 118,265 consecutive births of known outcome during the period from 1979 to 1987 in the area which is covered by our registry of congenital malformations. For each case a control was studied. The LRD was localised and classified according to the EUROCAT guide for the description and classification of limb defects. The prevalence of LRD was 1.04 per thousand: 82.9% of the babies were liveborn, 13.0% were late spontaneous abortion or stillborn and termination was performed in 4.0% of the cases. The proportion of males was 0.55. The most common malformations in the 51.2% of children who had at least one other anomaly than LRD were associated cardiac, digestive and renal anomalies. The pregnancy with limb anomalies was more often complicated by oligohydramnios, polyhydramnios and threatened abortion but there were no differences in parental characteristics. However, 9.7% of marriages were consanguineous (P less than 0.01) and the incidence of LRD in first-degree relatives of the children with LRD was high. First-degree relatives also had more non-limb malformations than did those of controls.