Smith‐Lemli‐Opitz syndrome in trisomy 13: How does the mix work?

BACKGROUND Trisomy 13 and Smith‐Lemli‐Opitz syndrome (SLOS) are both well‐recognized multiple congenital anomaly/mental retardation syndromes. CASE In this report we describe a male newborn with trisomy 13 who also has features of SLOS, such as 2/3 toe syndactyly and a shawl‐like scrotum. Biochemical analysis was consistent with SLOS, and limited molecular analysis revealed 1 mutation in the DHCR7 gene. CONCLUSIONS The challenges in establishing the diagnosis of SLOS in this patient are presented and the unique coexistence of the 2 major malformation syndromes is discussed. Given the overlapping phenotype of the 2 syndromes, our report should encourage further research on cholesterol biosynthesis in patients with trisomy 13. Birth Defects Research (Part A), 2005. © 2005 Wiley‐Liss, Inc.