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Obesity, especially with an early onset, is not only a health and social burden for the patient, it also plays an important role for the community in socioeconomic regard with the follow-up costs. Depending on the age there are about 10-18% of the children and adolescents in Germany overweight, about 4-8% are obese.
Regarding the interaction between exogenous factors like environmental factors and endogenous factors like disposition, genetic aspects gained in importance within the last years of research. With genome-wide linkage analyses concentrating on obesity and with investigations concerning non insulin dependent diabetes mellitus (NIDDM) it was possible to identify the gene CAPN10 and a haplotype combination in the chromosome region 2q37. This haplotype combination built by the polymorphisms SNP-43, -19 and -63 was identified as a "high risk" haplotype combination for NIDDM. It it near that CAPN10 could be associated with Obesity.
In the present study 166 families with 166 obese test persons, 193 obese siblings and their 166 parental pairs have been examined. Six polymorphisms in the CAPN10 gene and two microsatellite markers which flank the region were genotyped using polymerase chain reaction or by help of a semi-automatic sequencer.
A linkage analysis for the region was carried out and the allele frequencies as well as the haplotype frequencies were determined. The transmission rates of three polymorphisms which define the "high risk" haplotype combination, as well as the respective haplotypes were calculated performing a pedigree disequilibrium test. Furthermore we compared the haplotype combination of the children we estimated from the haplotype combinations of their parents with the actually observed haplotype combinations.
In this study no linkage between the CAPN10 region and early onset obesity could be proved. Association of allele frequency or genotype frequency with early onset obesity could not be pointed out. The frequencies of the haplotypes were very similar to the frequencies of other caucasian families. The transmission rates of the haplotypes and the haplotype combinations did not differ significantly from 50%. For the "high risk" haplotype combination 112/121 in particular no dependence on early onset obesity could be found.