Apparent Smith-Lemli-Opitz syndrome and Miller-Dieker syndrome in a family with segregating translocation t(7;17)(q34;p13.1)

We describe a family in which one male infant presented with Miller‐Dieker syndrome and four male relatives had a phenotype similar to the Smith‐Lemli‐Opitz (SLO) syndrome. High resolution cytogenetic analysis on the child with Miller‐Dieker syndrome showed 46, XY, −17, + der17t(7;17)(q34:p13.1). Paternal chromosomes showed a balanced translocation: 46, XY,t(7;17)(q34:p13.1). The paternal grandmother had a history of multiple miscarriages, and a paternal uncle had two sons who died neonatally. Chromosomes on these children and their father had originally been reported as normal. There was also a paternal cousin to the father of the propositus who had had two sons with similar clinical findings. A diagnosis of SLO syndrome was considered. Image enhancement techniques on previous suboptimal preparations on these four children documented the subtle unbalanced translocation 46, XY, − 7, + der7t(7;17)(q34:p13.1). Subsequent high resolution analysis on one of these four children who was still living confirmed this chromosome constitution. It is postulated that these apparent SLO cases may represent a contiguous gene syndrome in which SLO or a separate entity closely mimicking the syndrome in included.