De novo 1;10 balanced translocation in an infant with thanatophoric dysplasia: a clue to the locus of the candidate gene.

A female infant with thanatophoric dysplasia was found to have a de novo translocation involving chromosomes 1 and 10. The chromosome abnormality may represent an important clue in identifying the locus for the candidate gene responsible for this lethal skeletal dysplasia.

Greig cephalopolysyndactyly syndrome: altered phenotype of a microdeletion syndrome due to the presence of a cytogenetic abnormality.

A male had several features of Greig cephalopolysyndactyly syndrome (GCPS) and significant developmental delay. He was found to have a de novo chromosomal deletion of chromosome no. 7 involving p13; this resulted in loss of the zinc finger gene, GLI3, which is the candidate gene in this syndrome. Modification of the CGPS phenotype in a sporadic case emphasizes the importance of searching for a chromosomal origin of this autosomal dominant disorder. Detection of a chromosomal deletion in these patients may be associated with a poor prognosis from the standpoint of cognitive development, and the potential for other structural abnormalities not normally associated with GCPS.