Genetic linkage and imprinting effects on body mass index in children and young adults

Body mass index (BMI) is used as a measure of fatness. Here we performed a genome-wide scan for genes related to BMI, while allowing for the possible effects of imprinting. We applied a sib pair linkage analysis to a sample of primarily children and young adults by using the Haseman-Elston method, which we modified to model the separate effects of paternally and maternally derived genetic factors. After stratification of sib pairs according to age, a number of regions showing linkage with BMI were identified. Most linkage and imprinting effects were found in children 5 - 11 years of age. Strongest evidences for linkage in children were found on chromosome 20 at 20p11.2-pter near the marker D20S851 (LODTotal - 4.08, P = 0.000046) and near the marker D20S482 (LODTotal = 3.55, P = 0.00016), and Chromosome 16 at 16p13 near the marker ATA41E04 (LODTotal = 3.12, P = 0.00025), and those loci did not show significant evidence for imprinting. Six regions showing evidence of imprinting were 3p23 - p24 ( paternal expression), 4q31.1 - q32 ( maternal expression), 10p14 - q11 ( paternal expression), and 12p12-pter ( paternal expression) in children, and 4q31-qter ( paternal expression) and 8p ( paternal expression) in adults.