Associated anomalies in Pierre Robin sequence

Pierre Robin sequence (PRS) is frequently co-occurring with other non-PRS congenital anomalies. The types and the prevalence of anomalies co-occurring with PRS vary in the reported studies. The aims of this report was to study the types and the prevalence of the anomalies co-occurring with PRS in a well-studied population northeastern France. The types and the prevalence of anomalies co-occurring in cases with PRS were ascertained in all terminations of pregnancy, stillbirths and live births in 387,067 births occurring consecutively during the period 1979-2007 in the area covered by our registry of congenital anomalies which is population-based, 89 cases of PRS were registered during the study period with a prevalence of 2.29 per 10,000 births, 69.7% of the cases had associated non-PRS anomalies. Chromosomal abnormalities were present in 10 (11.2%) cases including three 22 q11.2 deletion. Non-chromosomal recognizable conditions were diagnosed in 27 cases (30.3%) including 10 Stickler syndrome, 8 Treacher Collins syndrome, 3 cases with short stature and 6 other syndromes. Multiple congenital anomalies (MCA) were present in 25 cases (28.1%). The most frequent MCA were in the ear, face and neck (35 out of 98 anomalies, 35.7%), cardiovascular (18 anomalies, 18.4%), musculoskeletal (11 anomalies, 11.2%), central nervous (7 anomalies, 7.1%), urinary (6 anomalies, 6.1%), and eye (6 anomalies, 6.1%) system. The high prevalence of associated anomalies justifies a thorough screening for other congenital anomalies in cases with PRS.

Shift in skin microbiota of Western European women across aging

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.

ASSOCIATED ANOMALIES IN CASES WITH LIMB REDUCTION DEFICIENCIES

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.

From the morphological to the transcriptomic characterization of a compromised three-dimensional in vitro model mimicking atopic dermatitis

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.

ASSOCIATED NON DIAPHRAGMATIC ANOMALIES AMONG CASES WITH CONGENITAL DIAPHRAGMATIC HERNIA

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.

Discordance for Skeletal and Cardiac Defect in Monozygotic Twins

A case of monozygotic male twins discordant for skeletal and cardiac defect is reported. One twin had the hemifacial microsomia type of the oculo-auriculo-vertebral dysplasia. The cotwin had no asymmetry of the face and normal ears, but preaxial polydactyly and ventricular and auricular septal defects. The cotwins were concordant for craniostenosis with a ridge metopic suture. Karyotypes were normal.

Associated malformations among infants with radial ray deficiency

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.

Bone status in a mouse model of genetic hemochromatosis

Genetic hemochromatosis is a cause of osteoporosis; mechanisms leading to iron-related bone loss are not fully characterized. We assessed the bone phenotype of HFE (-/-) male mice, a mouse model of hemochromatosis. They had a phenotype of osteoporosis with low bone mass and alteration of the bone microarchitecture.

INTRODUCTION

Genetic hemochromatosis is a cause of osteoporosis. However, the mechanisms leading to iron-related bone loss are not fully characterized. Recent human data have not supported the hypothesis of hypogonadism involvement. The direct role of iron on bone metabolism has been suggested.

METHODS

Our aim was to assess the bone phenotype of HFE (-/-) male mice, a mouse model of human hemochromatosis, by using microcomputed tomography and histomorphometry. HFE (-/-) animals were sacrificed at 6 and 12 months and compared to controls.

RESULTS

There was a significant increase in hepatic iron concentration and bone iron content in HFE (-/-) mice. No detectable Perls' staining was found in the controls' trabeculae. Trabecular bone volume (BV/TV) was significantly lower in HFE (-/-) mice at 6 and 12 months compared to the corresponding wild-type mice: 9.88 ± 0.82% vs 12.82 ± 0.61% (p = 0.009) and 7.18 ± 0.68% vs 10.4 ± 0.86% (p = 0.015), respectively. In addition, there was an impairment of the bone microarchitecture in HFE (-/-) mice. Finally, we found a significant increase in the osteoclast number in HFE (-/-) mice: 382.5 ± 36.75 vs 273.4 ± 20.95 ¢/mm(2) (p = 0.004) at 6 months and 363.6 ± 22.35 vs 230.8 ± 18.7 ¢/mm(2) (p = 0.001) at 12 months in HFE (-/-) mice vs controls.

CONCLUSION

Our data show that HFE (-/-) male mice develop a phenotype of osteoporosis with low bone mass and alteration of the microarchitecture. They suggest that there is a relationship between bone iron overload and the increase of the osteoclast number in these mice. These findings are in accordance with clinical observations in humans exhibiting genetic hemochromatosis and support a role of excess iron in relation to genetic hemochromatosis in the development of osteoporosis in humans.

Associated malformations in cases with congenital diaphragmatic hernia

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%).

Does the Bravo pH capsule affect esophageal motor function?

The aim of this study was to determine whether attachment of the Bravo pH monitoring capsule alters esophageal motility. Twenty normal subjects were studied with 36-channel high-resolution manometry before and after Bravo capsule placement. Subjects performed 10 5-mL water-swallows in both upright and supine positions and two 5-mL barium-swallows under fluoroscopy synchronized with manometry recordings. There was no significant change in basal esophagogastric junction (EGJ) pressure, EGJ relaxation pressure or peristaltic function before and after Bravo placement in either position. However, a 2-cm focus of augmented peristalsis was found corresponding to the position of the Bravo capsule. Ten subjects were aware of the capsule (7 had a mild foreign body sensation, 1 had mild discomfort, and 2 had chest pain altering daily activity or diet) while nine subjects were unaware of the capsule. Subjects who were aware of the capsule's presence exhibited a greater augmentation of peristalsis than those who were not (P < 0.05). Neither EGJ function nor peristaltic performance were significantly altered by the presence of a Bravo capsule. However, capsule presence was associated with a locus of augmented peristalsis and this phenomenon was most evident in subjects who perceived the presence of the Bravo capsule.

Associated malformations in patients with anorectal anomalies

Patients with congenital anorectal malformations (ARM) 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 prevalences at birth of associated malformations in patients of a geographically defined population with ARM which were collected between 1979 and 2003 in 334, 262 consecutive births. Of the 174 patients with ARM during the study period, 49.4% had associated malformations. Patients with associated malformations were further classified into groups with nonsyndromic multiple congenital anomalies; chromosomal abnormalities; nonchromosomal syndromes including Townes-Brocks, Walker-Warburg, Ivemark, Fetal alcohol, Klippel-Feil, Pallister-Hall, Facio-auriculo-vertebral spectrum, deletion 22q11.2; sequences, including OEIS, Pierre Robin and sirenomelia; and associations including VATER and MURCS. Malformations of the urogenital system (81.1%) and of the skeletal system (45.5%) were the most common other congenital anomalies occurring with ARM in multiply malformed patients without recognized entities, followed by malformations of the cardiovascular system, the digestive system, and the central nervous system. Weight, length, and head circumference of children with ARM and multiple associated malformations were lower than in controls, as was the weight of the placenta. Prenatal detection by fetal ultrasonographic examination was rarely made in isolated ARM. However, even in multiple associated malformations, prenatal detection by fetal ultrasonographic examination had a low sensitivity, 36%. In conclusion the overall prevalence of malformations, which was close to 1 in two infants, emphasizes the need for a thorough investigation of patients with ARM. A routine screening for other malformations may be considered in patients with ARM, and genetic counseling seems warranted in most of these complicated cases.

Comparison of esophageal acid exposure at 1 cm and 6 cm above the squamocolumnar junction using the Bravo pH monitoring system

The aim of this study was to assess the quantitative differences of acid exposure at 1 cm and 6 cm above the squamocolumnar junction (SCJ) using two radiotelemetry pH capsules affixed to the esophageal mucosa. Ten normal subjects and 10 endoscopy-negative gastroesophageal reflux disease (GERD) patients without hiatus hernia (ages 20-54, 12 male) were studied for a 24-h period using the Bravo pH monitoring system. pH capsules were placed 1 cm and 6 cm above the SCJ. Interpretable data for at least 14 h was obtained in 18 of the 20 subjects (9 normal, 9 GERD). Two failures occurred secondary to early capsule dislodgement. Median esophageal acid exposure was significantly increased at 1 cm above the SCJ compared to 6 cm above the SCJ during the total, upright and postprandial time periods in both normal and GERD subjects. During a 2 h postprandial period the esophageal acid exposure was 8-fold greater in GERD subjects and 5-fold greater in normal subjects 1 cm above the SCJ compared to 6 cm above the SCJ. Confident measurement of esophageal acid exposure at a fixed position 1 cm above the SCJ is feasible with the Bravo system. Acid exposure was significantly higher 1 cm above the SCJ compared to 6 cm above the SCJ in both GERD patients and controls. These findings suggest that measurement of acid exposure 1 cm above the SCJ may improve accuracy of pH monitoring by detecting acid reflux events confined to the distal esophagus.

Acid reflux event detection using the Bravo wireless versus the Slimline catheter pH systems: why are the numbers so different?

OBJECTIVE

This study analysed the relative accuracy of the Bravo wireless and the Slimline catheter-Mark III Digitrapper pH systems in the detection of acid reflux events.

METHODS

Twenty five asymptomatic subjects were studied. A Bravo capsule was placed 6 cm above the squamocolumnar junction (SCJ), marked by an endoclip, and a Slimline pH catheter was placed 5 cm above the manometrically localised lower oesophageal sphincter. The distance between the SCJ and each pH electrode was measured fluoroscopically. An in vivo pH reference was established using swallows of orange juice (pH 3.88). Concurrent pH data from the two systems were analysed in Excel spreadsheets.

RESULTS

Significantly more acid reflux events were reported by the Digitrapper system than the Bravo system (117.0 v 41.8). This was not explained by electrode position as there was no difference in median distance between the SCJ and either pH electrode (7.25 cm v 7.08 cm). The dominant source of discrepancy between systems was inaccuracy in electrode calibration and, after adjustment using the in vivo orange juice pH measurement, the discrepancy improved by 40%. However, discrepancy still existed and was most pronounced with short reflux events (1-15 s for the catheter, 1-17 s for the Bravo) associated with minimal intraoesophageal acidity and poor concordance between systems.

CONCLUSION

Substantially more reflux events were reported by the Digitrapper system compared with the Bravo system; 40% of excess events were attributable to a flawed software scheme for electrode thermal calibration while most of the remainder were brief events with poor reproducibility between systems.

Epidemiology of Down syndrome in 118,265 consecutive births

The epidemiology of Down syndrome (DS) was studied in the area which is covered by our registry of congenital malformations. For each of the 139 new DS cases which were ascertained during the period 1979 to 1987 more than 50 factors were studied and compared to those from control infants. The prevalence of DS was 1.17%; 3.6% of the DS cases were stillbirths and 14.4% were induced abortions. Karyotypes were obtained in 137 cases of which all but 7 were 47, + 21, 4 were mosaics (2.8%), and 5 had translocations (3.6%). Interchromosomal effect was a question in 3 cases. The most common types of associated malformations were cardiac anomalies (44.6%) and intestinal atresia. We did not observe seasonality or time/space clusters in spite of the Chernobyl nuclear accident. No paternal age effect was demonstrated. In our material the first-born infants were at lower risk of DS than the later born. Five percent of the mothers of DS had 2 previous spontaneous abortions (controls 2.8%). At birth, the DS infants measured less and their head circumference was lower than in control infants. Weight of placenta was also lower than in control infants. In our material there were 7.9% of consanguineous marriages (P = .010). The pregnancies of the DS children were often complicated by threatened abortions; 6.4% of the mothers of the DS children were diabetic (P = .069). For all other factors studied no statistically significant difference with respect to controls could be demonstrated.

A vulnerability locus to multiple sclerosis maps to 7p15 in a region syntenic to an EAE locus in the rat

Multiple sclerosis (MS) is a chronic immune-mediated demyelinating disease of the central nervous system. Evidence from family studies indicates a strong genetic component. Despite many studies of candidate genes, only an association with the HLA-DRB1*1501-DQB1*0602 haplotype has been generally detected, and HLA linkage established by transmission disequilibrium testing. A genome-wide scan revealed suggestive linkage of MS with markers on chromosome 7p15 in HLA-DR15-nonsharing British families, in a region syntenic to a locus predisposing to experimental autoimmune encephalomyelitis in the rat. We therefore tested the 7p15 region as a candidate region for genetic susceptibility to MS in 104 French families with at least two affected siblings. We found evidence suggestive of a predisposing locus in families in which only one affected sibling or none of them carry the HLA-DR15 allele. Comparison of the results of the British and French groups suggests that the region of interest can be narrowed to a 2.45-cM interval.

Duodenal mRNA expression of iron related genes in response to iron loading and iron deficiency in four strains of mice

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.

Impact of prenatal diagnosis on livebirth prevalence of children with congenital anomalies

The objectives of this study were to describe the impact of prenatal diagnosis on the birth prevalence of congenital anomalies over 21 years (1979-1999) in a well defined population in northeastern France (13,500 births per year). The material for this study came from the analysis of data from multiple sources on births and terminations of pregnancy after prenatal diagnosis of congenital anomalies in 279,642 consecutive pregnancies of known outcome. The study period was divided into three subgroups 1979-1988, 1989-1993 and 1994-1999. Between 1979-1988, 1989-1993 and 1994-1999, prenatal detection of congenital anomalies increased, respectively, from 12.0% to 25.5% and to 31.7%. Termination of pregnancy (TOP) increased in the same proportions during the three time periods. However, the increase of TOP was much higher for chromosomal anomalies than for nonchromosomal congenital anomalies. The birth prevalence of Down's syndrome fell by 80% from 1979-1988 to 1994-1999. Sensitivity of prenatal detection of congenital anomalies and TOPs were lower for isolated cases (only one malformation present in the fetus) than for multiple malformations in the same fetus. Sensitivity varied with the type of malformations: it was high for neural tube defect (79.7%) and urinary anomalies (50.7%) and low for congenital heart defects (16.4%). In conclusion, the introduction of routine prenatal diagnosis has resulted in a significant fall in the birth prevalence of children with congenital anomalies. However, this fall varied with the types of congenital anomalies.

Risk factors in congenital abdominal wall defects (omphalocele and gastroschisi): a study in a series of 265,858 consecutive births

The aim of this study was to describe the prevalence at birth of two abdominal wall defects (AWD), omphalocela and gastroschisis and to identify possible etiologic factors. The AWD came from 265,858 consecutive births of known ouome registered in the registry of congenital malformations of Strasbourg for the period 1979 to 1998. Request information on the child, the pregnancy, the parents and the family was obtained for cases and for controls. Hundred five cases with AWD were analysed, 55.2 % were omphalocele and 44.8 % were gastroschisis. The mean prevalence rate for omphalocele was 2.18 per 10,000 and for gastroschisis 1.76 per 10,000. Associated malformations were found in 74.1 % of omphalocele compared with 53.2 % of gastroschisis; 29.3 % of fetuses with omphalocele had an abnormal karyotype, 44,8 % had a recognizable syndrome, association or an unspecified malformation pattern; 51.0 % of fetuses with gastroschisis had additional malformations that were not of chromosomal origin, but 1 case. Antenatal ultrasound examination was able to detect 39 (67.2 %) cases of omphaloceles and 27 (57.4 %) cases of gastroschisis. In 30 (51.7 %) cases of omphalocele and in 7 (14.9 %) cases of gastroschisis parents opted for termination of pregnancy. The overall survival rate was 14 (24.1 %) for omphalocele and 30 (63.8 %) for gastroschisis. Weight, length and head circumference at birth of infants with AWD were less than those of controls. The weight of placenta of infants with AWD was not different from the weight of placenta of controls. Gastroschisis was associated with significantly younger maternal age than omphalocele. Pregnancies with AWD were more often complicated by threatened abortion, oligohydramnios and polyhydramnios. Mothers of children with AWD took more often medication during pregnancy than mothers of controls.

No evidence for transmission disequilibrium between a new marker at the myelin basic protein locus and multiple sclerosis in French patients

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.

Genetic markers of immunoglobulins and diabetes mellitus in the multiracial population of New Caledonia. The CALDIA Study Group

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.

Associated malformations in cases with oral clefts

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.

Study of 290 Cases of Polyhydramnios and Congenital Malformations in a Series of 225,669 Consecutive Births

OBJECTIVES

To provide data on polyhydramnios associated with congenital anomalies in 225,669 consecutive pregnancies.

MATERIAL AND METHODS

The information in this study came from births of known outcome recorded in our registry of congenital malformations. Routine ultrasonographic examination was performed. Polyhydramnios was diagnosed ultrasonographically. A case-control study allowed the examination of genetic and environmental causal factors of polyhydramnios associated with congenital malformations.

RESULTS

The prevalence of this association was 1.28/1,000 (290 cases). Polyhydramnios associated with congenital malformations was diagnosed prenatally in 44.5% of the cases, 10.3% of the infants were stillborn. Forty-one percent of the cases had more than one malformation, 14.5% had a chromosomal aberration, and 20.0% had multiple malformations that do not constitute a syndrome. The more frequent malformations associated with polyhydramnios were cardiac, digestive, central nervous system, musculoskeletal, and urinary. There was increased parental consanguinity. The incidence of polyhydramnios and congenital anomalies among first-degree relatives was 4.1% and first-degree relatives had more malformations than controls (6.2 vs. 3.2%, p < 0.05). Threatened abortions and diabetes mellitus were significantly more frequent among mothers of children with congenital malformations associated with polyhydramnios than among controls.

CONCLUSIONS

Our study demonstrated that careful fetal examination has to be performed when polyhydramnios is diagnosed as congenital malformations are often associated with polyhydramnios. We recommend the use of fetal chromosome analysis and careful ultrasonographic examination in every pregnancy complicated by polyhydramnios.

Parental consanguinity as a cause for increased incidence of births defects in a study of 238,942 consecutive births

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, (p < 0.001). 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 (p < 0.01) 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.

A genome-wide search identifies two susceptibility loci for experimental autoimmune encephalomyelitis on rat chromosomes 4 and 10

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.

Study of Down syndrome in 238,942 consecutive births

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% p < 0.05). 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 (P < 0.01). 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.

Risk factors in congenital anal atresias

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 (p < 0.05). 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.

Study of 224 Cases of Oligohydramnios and Congenital Malformations in a Series of 225,669 Consecutive Births

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.

Conservation of ancestral haplotypes telomeric of HLA-A

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.

Heterogeneity in rates of recombination in the 6-Mb region telomeric to the human major histocompatibility complex

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.

Prevalence of neural tube defects in northeastern France, 1979-1994. Impact of prenatal diagnosis

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.

Congenital eye malformations in 212,479 consecutive births

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.

Evaluation of prenatal diagnosis of congenital gastro-intestinal atresias

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 at > or = 18 weeks gestation and to train sonographers in order to improve prenatal detection of GIA.

Polymorphic tri- and tetranucleotide repeats in exons 1 and 8 of the myelin oligodendrocyte glycoprotein (MOG) gene

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.

Evaluation of routine prenatal diagnosis by a registry of congenital anomalies

Prenatal diagnosis performed by ultrasound scan is now a routine part of prenatal care in many countries. How many fetal anomalies are actually detected by these procedures? We have used our registry of congenital malformations to answer this question. In a previous study (Prenat. Diagn., 12, 263-270, 1992), considering the period 1979-1988, we have shown that prenatal diagnosis was performed in 23.1 per cent of fetuses with a chromosomal aberration and in 20.1 per cent of fetuses with non-chromosomal anomalies. In 1991 and 1992, the percentage of termination for Down syndrome was 44.4 and 41.9 per cent, respectively. From 1989 to 1992, the detection rate and the specificity of prenatal diagnosis by ultrasonographic examination were improved. The detection rate for isolated malformations (fetuses with only one anomaly) and for multiple malformed children was 26.2 and 66.0 per cent, respectively. The detection rate of congenital anomalies by ultrasonography was variable for the different categories of malformation. A high detection rate was observed for anencephaly (100 per cent) and urinary tract malformation. A low detection rate was seen for cleft lip (17.5 per cent) and limb reduction defects (18.2 per cent).

Myelin oligodendrocyte glycoprotein (MOG) gene polymorphisms and multiple sclerosis: no evidence of disease association with MOG

The region surrounding the myelin oligodendrocyte glycoprotein (MOG) gene, located telomeric to the major histocompatibility complex on chromosome 6, was shown to contain three highly informative microsatellites. To examine the potential role of variants of the MOG gene in susceptibility to multiple sclerosis, these CA-repeat polymorphic markers were characterized on a sample of 169 multiple sclerosis patients and 173 healthy unrelated individuals by a method combining fluorescence labelling of PCR products and use of an automated DNA sequencer. Both patients and controls lived in the southwest of France (in the Pyrénées-Atlantiques) and had similar ethnic background. The distribution of the MOG haplotypes was not significantly different in the two groups (P = 0.38). This is not in favour of the implication of the MOG gene in the genetic component of multiple sclerosis, unless different independent mutations have occurred within this gene.

Three highly polymorphic microsatellites at the human myelin oligodendrocyte glycoprotein locus, 100 kb telomeric to HLA-F. Characterization and relation to HLA haplotypes

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.

The human myelin oligodendrocyte glycoprotein (MOG) gene: complete nucleotide sequence and structural characterization

Human myelin oligodendrocyte glycoprotein (MOG), a myelin component of the central nervous system, is a candidate target antigen for autoimmune-mediated demyelination. We have isolated and sequenced part of a cosmid clone that contains the entire human MOG gene. The primary nuclear transcript, extending from the putative start of transcription to the site of poly(A) addition, is 15,561 nucleotides in length. The human MOG gene contains 8 exons, separated by 7 introns; canonical intron/exon boundary sites are observed at each junction. The introns vary in size from 242 to 6484 bp and contain numerous repetitive DNA elements, including 14 Alu sequences within 3 introns. Another Alu element is located in the 3'-untranslated region of the gene. Alu sequences were classified with respect to subfamily assignment. Seven hundred sixty-three nucleotides 5' of the transcription start and 1214 nucleotides 3' of the poly(A) addition sites were also sequenced. The 5'-flanking region revealed the presence of several consensus sequences that could be relevant in the transcription of the MOG gene, in particular binding sites in common with other myelin gene promoters. Two polymorphic intragenic dinucleotide (CA)n and tetranucleotide (TAAA)n repeats were identified and may provide genetic marker tools for association and linkage studies.

Prenatal detection of internal urinary system's anomalies. A registry-based study

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.

Prevalence of neural tube defects in northeastern France, 1979-1992 impact of prenatal diagnosis

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.

Evaluation of prenatal diagnosis of limb reduction defects by a registry of congenital anomalies

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 limb reduction defects (LRDs). The mean time of detection of LRDs was 26 weeks of pregnancy (range 16-32 weeks). The sensitivity of prenatal diagnosis of LRDs by ultrasonographic examination was much lower for isolated malformations (fetuses with only one anomaly) than for multiply malformed children with LRDs, 4.0 and 18.2 per cent, respectively. For all cases of LRDs, the percentage of prenatal detection was 11.5. Termination of pregnancy was performed in 6.7 per cent of the cases.

Tumor necrosis factor polymorphism in multiple sclerosis: no additional association independent of HLA

In order to investigate whether genes coding for tumor necrosis factors (TNF) contribute to the pathogenesis of multiple sclerosis (MS) and also whether they have a non-random association with the MS associated HLA-DRB1*1501-DQA1*0102-DQB1*0602 haplotype, 40 MS patients and their parents were characterized at four polymorphic loci in the region of the TNF genes: a NcoI RFLP and three microsatellites. We were able to determine the parental haplotypes and used those which were not transmitted to the proband as controls. Fifty percent of the HLA-DRB1*1501-DQA1*0102-DQB1*0602 haplotypes carried the TNFc1-n2-a11-b4 allelic combination in both the patient and the control groups. However, there was no association of any of these TNF polymorphisms with MS, independent of that already described for the class II region. This, with the lack of association of DP alleles with MS, effectively marks the boundaries of the MS associated haplotype.

[Genetics of autoimmune diseases]

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.