Is Dandy-Walker malformation associated with "distal 13q deletion syndrome"? Findings in a fetus supporting previous observations.

We report on a fetus with a large deletion of the distal part of the long arm of chromosome 13, (del(13)(q14 --> qter)) congenital anomalies of the urinary system, lungs and extremities, and Dandy-Walker malformation (DWM). Although DWM has been associated with many chromosomal abnormalities and genetic syndromes, its relation to the distal 13q has been demonstrated recently. In 2002, McCormack et al., described two patients with deletions of the long arm of chromosome 13 who had multiple congenital abnormalities along with holoprosencephaly (HPE) and DWM. The phenotypic features and autopsy findings of a fetus with "distal 13q deletion syndrome" at 22 weeks gestation are discussed and comparison with the previous two cases is made. The findings support the previous hypothesis suggesting that haploinsufficiency at a locus within 13q22-33 due to microdeletions may be responsible for isolated DWM in some of the patients. Detailed examination of 13q (13q22-33) by means of conventional and molecular cytogenetic methods is necessary in cases with DWM.