Novel heterozygous mutation in in an infant with hypocalcemic seizures.

Patients with 22q11.2 deletion syndrome have characteristic facial appearance, palate abnormalities, hypoparathyroidism, thymic hypoplasia, and congenital heart disease. The 22q11.2 region includes and 30 other genes. Analysis of transgenic mice showed that was associated with the 22q11.2 deletion syndrome. In humans, mutations have been reported in 22q11.2 deletion-negative patients with velocardiofacial syndrome or DiGeorge syndrome. Genotype-phenotype correlations are not fully understood in these patients. We report the case of an infant with a novel heterozygous mutation who experienced hypocalcemic seizures. This patient had no palate abnormalities, cardiac anomalies, or the typical facial appearance observed in 22q11.2 deletion syndrome. The presence of thymic hypoplasia prompted us to perform G-banding, fluorescent hybridization, and subsequent analysis. We emphasize the importance of diagnosing thymic hypoplasia in hypocalcemic infants without 22q11.2 deletion for detecting mutations.