Deletion of chromosome 3q proximal region gives rise to a variable phenotype.

We report two new cases with interstitial deletions of chromosome 3. Both had breakpoints established as q12q21. Despite an apparently identical abnormal karyotype, their phenotypes were different although hypotonia, severe developmental delay, lack of speech, high arched palate and pointed chin were common features. One patient had corpus callosum agenesis (ACC), also present in two of the only four previously reported cases with a deletion in this region.