A 797 kb de novo deletion of 18q21.31 in a patient with speech delay, mental retardation, sleeping problems, facial dysmorphism, and feet anomalies.

We report a 797 kb de novo interstitial deletion of 18q21.31 in a 6-year-old boy with speech delay, mental retardation, sleeping problems, facial dysmorphism, and feet anomalies. Examination of the region showed two genes, TXNL1 and WDR7, to be involved in the deletion. Haploinsufficiency of these genes could potentially contribute to the phenotype. Our patient has some clinical features that overlap with earlier described patients with a larger deletion of the distal part of chromosome 18q. The small deletion in region 18q21.31 may be responsible for some of the common features found in patients with larger 18q deletions.