Microsatellites proximal to leptin and leptin receptor as risk factors for spina bifida

Several recent studies have observed an association between neural tube defect risk and prepregnant obesity. This association was generally stronger for spina bifida and was observed irrespective of additional maternal factors, including periconceptional intake of vitamin supplements. Other studies have identified mutations within the genes that code for leptin (LEP) and its receptor (LEPR), which have been linked to obesity in mice and humans. We investigated the potential association between nucleotide variation at the LEP and LEPR loci, and increased risk of spina bifida. We searched specifically for allelic association at a pair of highly polymorphic microsatellites closely linked to either the LEP or LEPR gene. Data were derived from a population-based case-control study that had previously identified an association between a woman's prepregnant obesity and her risk of delivering an infant with spina bifida. A total of 56 spina bifida case infants and 126 nonmalformed control infants were genotyped for 10 microsatellite alleles closely linked to the LEP gene, and 49 cases and 125 controls were genotyped for 10 microsatellite alleles closely linked to the LEPR gene. In general, alleles were not observed to be exclusively associated with substantially greater spina bifida risk in the body mass index (BMI) category (obese) of >29 kg/m(2) compared with the BMI category (nonobese) of 29 kg/m; (2) having either allele and BMI 29 kg/m(2). The odds ratios (95% confidence interval) for these comparisons were: for allele 257, 4.5 (1.1-19.4), 1.9 (0.5-6.3), and 2.9 (1.3-6.4), respectively, and for allele 271, 6.7 (1.6-30.4), 2.7 (0.7-10.9), and 2.7 (1.2-5.9), respectively. Owing to the exploratory nature of this investigation, the significance of these latter results is unclear.