Molecular analysis of a patient with neurofibromatosis 1 and achondroplasia

The gene for von Recklinghausen neurofibromatosis (NF1) is on proximal 17q; the location of the gene for achondroplasia (ACH) is unknown. We have begun a molecular analysis of a patient with mental retardation, NF1 and ACH, a clinical presentation suggestive of a contiguous gene syndrome. In addition, this individual has a 47,XYY chromosome constitution. To define a possible chromosome 17 deletion, we investigated the copy number of DNA sequences linked to NF1 with conventional and pulsed-field gel electrophoresis (PFGE). We found no evidence for a deletion on chromosome 17. These results make it unlikely that this patient harbors a single deletion in the NF1 region causing both NF1 and ACH and suggest different mechanisms for the de novo occurrence of 2 autosomal dominant disorders in this individual.