Patients with Down syndrome tend to have poor motor development, lower than average I.Q.'s, and a higher than normal incidence of Alzheimer's disease later in life. Rarely, this condition is associated with a translocation of part of chromosome 21 to either chromosome 14 or 22. For this reason, infants with Down syndrome should have chromosomal analysis to rule out a transmissible defect that may be carried by other family members. Descriptions of these disorders can be found in Pediatric or Medical Genetics textbooks. This leads to a condition called hermaphroditism characterized by the presence of both ovarian and testicular tissues - typically an ovary on one side and a testicle on the other.
External genitalia are often ambiguous.
The majority are 46,XX with a partial Y chromosome hidden in an X chromosome. This latter situation is thought to arise from abnormal crossing over between X and Y chromosomes during the first stage of meiosis in spermatogenesis. In contrast to hermaphroditism which are chromosomal disorders, other disorders of sex differentiation can result from nongenetic environmental factors. The most common underlying explanation for this problem is an adrenal tumor. Testes are located in the abdomen or in the inguinal canals.