Down syndrome human karyotype 47,XY,+21
Down syndrome karyotype (formerly called trisomy 21 syndrome or
mongolism), human male, 47,XY,+21. This male has a full chromosome
complement plus an extra chromosome 21. Symptoms include a varying
degree of mental retardation, growth failure, muscular hypotoicity,
flay occiput, large tongue, slanting eyes, simian palmar crease,
intestinal and heart problems, and acute leukaemia. Older survivors
often develop Alzheimer's disease in their fourth or fifth decade.
The syndrome is associated with advanced maternal age.