A genetic disorder, originally identified by John Langdon Down (1826-1896), with congenital symptoms of hypotonia and minor physical stigmata, later characterized by some cognitive impairment, gross overeating that can lead to obesity, adipositas, hypogenitalism, and various other symptoms not always present such as self-mutilation of the face. The syndrome occurs in about 1/15000 births and is evident in all ethnicities as well as males and females. It is associated with loss of paternal alleles at chromosome 15q11-13.
See Allele, Autism, Angelman syndrome, Behavioral phenotype syndromes, Chromosome, Hypotonia, Methylation