Early onset hypocalcemia, which may be
asymptomatic, associated with hyperphosphatemia. Very low parathyroid
hormone levels, and possibly low growth hormone and insulin-like growth
factor. Consequently, patients have retarded growth (more than 2 SD
[standard deviations] below the mean). Facial dysmorphism is very
consistent, especially within families with more than one affected child:
microcephaly, deep-set eyes, depressed nasal bridge with beaked nose, long
philtrum, thin upper lip, micrognathia, and large, floppy ear lobes. Most
children have skeletal defects, such as medullary stenosis. Developmental
delay is usual. Seizures may occur. Reduced numbers of some T-cell subsets
have been detected in some patients, but immunological function seems
normal.