DNAJC6 and obesity due to melanocortin 4 receptor deficiency: Mutations in the DNAJC6 gene have been associated with mental retardation and Parkinson disease; early-onset obesity, mental retardation, and epilepsy were found in 7-year-old children with a homozygous 80 kb deletion in the chromosomal 1p31.3 region [12,13,14].