18p--syndrome resulting from 14q/18q 'dicentric' fusion translocation.

A child with nasal hypoplasia, growth and developmental delay, and 18p--due to 14q/18q apparent dicentric fusion is reported. Review of ten previously reported patients with 18p--due to fusion translocations involving the long arm of chromosome 18 reveals clinical features ranging from arrhinencephaly to minimal dysmorphic changes and mild retardation. This spectrum of clinical expression is similar to that seen in patients with partial 18p deletions. Since the same range of clinical features is observed whether there is partial or apparent total deletion of 18p, it is suggested that only a distal segment of the short arm of chromosome 18 may be etiologically related to the clinical phenotype in the 18p--syndrome.