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.

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.

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 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.

UNLABELLED: 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%).

Summary of contributions to GAW15 Group 16: processing/normalization of expression traits.

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.

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.

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.

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.

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.

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 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.