SIDDT: Sudden infant death with dysgenesis of testes.
SIDDT is an autosomal recessive syndrome that was first identified in an Old Order Amish community in Pennsylvania. Over two generations, nine families from this community had lost 21 infants to sudden death. All infants with SIDDT died before 12 months of age of abrupt cardiac and respiratory arrest. Males with SIDDT may also have underdeveloped testes. Females appear to be normal. Male and female infants with SIDDT died suddenly at the same age.
The gene responsible for SIDDT is on chromosome 6. The gene called TSPYL is expressed both in the brainstem and in testes. DNA sequencing of the gene in four children with SIDDT revealed mutations in TSPYL. All affected infants had two abnormal copies of the TSPYL gene and all parents were carriers of one copy of the mutant TSPYL gene.