Claude Stoll

Geographical and ethnic variation of the 677C>T allele of 5,10 methylenetetrahydrofolate reductase ( MTHFR ): findings from over 7000 newborns from 16 areas world wide

Since its biochemical characterisation in 19911 and its genetic identification in 1995,2 677C>T allele (T allele) of the 5,10 methylenetetrahydrofolate reductase ( MTHFR ) gene has been a focus of increasing interest from researchers world wide. The expanding spectrum of common conditions linked with the 677C>T allele now includes certain adverse birth outcomes (including birth defects), pregnancy complications, cancers, adult cardiovascular diseases, and psychiatric disorders.3–8 Although several of these associations remain unconfirmed or controversial,4 their scope is such that it becomes of interest to explore the geographical and ethnic distribution of the allele and associated genotypes.9 Accurate information on such distribution can contribute to studies of gene-disease associations (by providing reference population data) and population genetics (by highlighting geographical and ethnic variations suggestive of evolutionary pressures),10 as well as help to evaluate health impact (by allowing estimates of population attributable fraction). Current population data, however, show gaps and even for some ethnic groups or large geographical areas (for example, China) few data are available.3 Our aim was to supplement the available data by collecting a large and diverse sample of newborns from different geographical areas and ethnic groups, and to examine international variations in the distribution of the 677C>T allele. We present findings relating to more than 7000 newborns from 16 areas around the world. The study was conducted under the auspices of the International Clearinghouse for Birth Defect Monitoring Systems (ICBDMS) and was coordinated through its head office, the International Center on Birth Defects (ICBD). ### Sample selection Participating programmes, in consultation with the coordinating group, identified a population sampling approach that would be simple yet minimise sampling bias with respect to the MTHFR genotype. We made an explicit attempt to sample systematically the newborn population. Details of each programme’s approach are listed below, and further …

Prenatal diagnosis of severe structural congenital malformations in Europe.

To assess at a population‐based level the frequency with which severe structural congenital malformations are detected prenatally in Europe and the gestational age at detection, and to describe regional variation in these indicators.

International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?

Abstract Objectives To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects. Design Retrospective cohort study of births monitored by birth defect registries. Setting 13 birth defects registries monitoring rates of neural tube defects from 1988 to 1998 in Norway, Finland, Northern Netherlands, England and Wales, Ireland, France (Paris, Strasbourg, and Central East), Hungary, Italy (Emilia Romagna and Campania), Portugal, and Israel. Cases of neural tube defects were ascertained among liveborn infants, stillbirths, and pregnancy terminations (where legal). Policies and recommendations were ascertained by interview and literature review. Main outcome measures Incidences and trends in rates of neural tube defects before and after 1992 (the year of the first recommendations) and before and after the year of local recommendations (when applicable). Results The issuing of recommendations on folic acid was followed by no detectable improvement in the trends of incidence of neural tube defects. Conclusions Recommendations alone did not seem to influence trends in neural tube defects up to six years after the confirmation of the effectiveness of folic acid in clinical trials. New cases of neural tube defects preventable by folic acid continue to accumulate. A reasonable strategy would be to quickly integrate food fortification with fuller implementation of recommendations on supplements.

The spectrum of congenital anomalies of the VATER association: An international study

The spectrum of the VATER association has been debated ever since its description more than two decades ago. To assess the spectrum of congenital anomalies associated with VATER while minimizing the distortions due to small samples and referral patterns typical of clinical series, we studied infants with VATER association reported to the combined registry of infants with multiple congenital anomalies from 17 birth defects registries worldwide that are part of the International Clearinghouse for Birth Defects Monitoring Systems (ICB-DMS). Among approximately 10 million infants born from 1983 through 1991, the ICB-DMS registered 2,295 infants with 3 or more of 25 unrelated major congenital anomalies of unknown cause. Of these infants, 286 had the VATER association, defined as at least three of the five VATER anomalies (vertebral defects, anal atresia, esophageal atresia, renal defects, and radial-ray limb deficiency), when we expected 219 (P<0.001). Of these 286 infants, 51 had at least four VATER anomalies, and 8 had all five anomalies. We found that preaxial but not other limb anomalies were significantly associated with any combination of the four nonlimb VATER anomalies (P<0.001). Of the 286 infants with VATER association, 214 (74.8%) had additional defects. Genital defects, cardiovascular anomalies, and small intestinal atresias were positively associated with VATER association (P<0.001). Infants with VATER association that included both renal anomalies and anorectal atresia were significantly more likely to have genital defects. Finally, a subset of infants with VATER association also had defects described in other associations, including diaphragmatic defects, oral clefts, bladder exstrophy, omphalocele, and neural tube defects. These results offer evidence for the specificity of the VATER association, suggest the existence of distinct subsets within the association, and raise the question of a common pathway for patterns of VATER and other types of defects in at least a subset of infants with multiple congenital anomalies.

Birth prevalence rates of skeletal dysplasias

This study establishes the prevalence rates at birth of the skeletal dysplasias which can be diagnosed in the perinatal period or during pregnancy. Using a population‐based register of congenital anomalies, a prevalence rate of 3.22 0/000 was observed. The most frequent types of skeletal dysplasia were achondroplasia and osteogenesis imperfecta (0.64 0/000, 1/15 000 births), thanatophoric dysplasia and achondrogenesis (0.28 0/000). The mutation rate for achondroplasia was higher in our material than in the other studies: 3.3 times 10‐5 per gamete per generation. Our study demonstrates that prenatal diagnosis by ultrasound is possible in some skeletal dysplasias.

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.

Evaluation of prenatal diagnosis of cleft lip with or without cleft palate and cleft palate by ultrasound: experience from 20 European registries

Ultrasound scans in the mid‐trimester of pregnancy are now a routine part of antenatal care in most European countries. Using data from registries of congenital anomalies a study was undertaken in Europe. The objective of the study was to evaluate prenatal detection of cleft lip with or without cleft palate (CL(P)) and cleft palate (CP). All CL(P) and CPs suspected prenatally and identified at birth in the period 1996–98 were registered from 20 Congenital Malformation Registers from the following European countries: Austria, Croatia, Denmark, France, Germany, Italy, Lithuania, Spain, Switzerland, The Netherlands, UK, Ukraine. These registries followed the same methodology. A total of 709 027 births were covered; 7758 cases with congenital malformations were registered. Included in the study were 751 cases reported with facial clefts: 553 CL(P) and 198 CP. The prenatal diagnosis by transabdominal ultrasound of CL(P) was made in 65/366 cases with an isolated malformation, in 32/62 cases with chromosomal anomaly, in 30/89 cases with multiple malformations and in 21/36 syndromic cases. The prenatal diagnosis of CP was made in 13/198 cases. One hundred pregnancies were terminated (13%); in 97 of these the cleft was associated with other malformations. Copyright

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.

Genetic and environmental factors in hypospadias.

A case control study of hypospadias was performed from 1979 to 1987 in Alsace, north-eastern France. A total of 176 out of 60 847 male infants had hypospadias giving a prevalence at birth of 2.89 per 1000 male newborns; 15.3% of all infants with hypospadias also had other malformations. Renal and urinary tract malformations were present in 37.0% of the infants with hypospadias and other additional malformations. None of the numerous aetiological factors which were studied was correlated with hypospadias except low weight of the placenta. The recurrence risk for brothers was 17.0% (an empirical risk of about 1 in 6) and the heritability coefficient was 56.9%. First degree relatives of infants with hypospadias had more malformations other than hypospadias than controls. These results have to be taken into consideration for genetic counselling.

Omphalocele and gastroschisis and associated malformations

The etiology of gastroschisis and omphalocele is unclear and their pathogenesis is controversial. Because previous reports have inconsistently noted the type and frequency of malformations associated with omphalocele and gastroschisis, we assessed these associated malformations ascertained between 1979 and 2003 in 334,262 consecutive births. Of the 86 patients with omphalocele, 64 (74.4%) had associated malformations. These included patients with chromosomal abnormalities (25, 29.0%); non‐chromosomal syndromes including Beckwith–Wiedemann syndrome, Goltz syndrome, Marshall–Smith syndrome, Meckel–Gruber syndrome, Oto‐palato‐digital type II syndrome, CHARGE syndrome, and fetal valproate syndrome; malformation sequences, including ectopia cordis, body stalk anomaly, exstrophy of bladder, exstrophy of cloaca, and OEIS (Omphalocele, Exstrophy of bladder, Imperforate anus, Spinal defect); malformation complexes including Pentalogy of Cantrell, and non‐syndromic multiple congenital anomalies (MCA) (26, 30.2%). Malformations of the musculoskeletal system (31, 23.5%), urogenital system (27, 20.4%), cardiovascular system (20, 15.1%), and central nervous system (12, 9.1%) were the most common other congenital malformations in patients with omphalocele and non‐syndromic MCA. Of the 60 patients with gastroschisis, 10 (16.6%) had associated malformations. In contrast to omphalocele, gastroschisis was rarely associated with a complex pattern of malformation, that is, one each (1.7%) with a chromosomal abnormality (trisomy 21), sequence (amyoplasia congenita), unspecified dwarfism, and 7 (11.7%) with MCA. We observed a striking difference in the prevalence of total malformations (74.4% vs. 16.6%, P < 0.001) and specific patterns of malformations associated with omphalocele and gastroschisis which emphasizes the need to evaluate all patients with omphalocele and gastroschisis for possible associated malformations. Malformation surveillance programs should be aware that the malformations associated with omphalocele can be often classified into a recognizable malformation syndrome or pattern (44.2%).