Abstract
We have studied two unrelated boys with isolated left mirror hand and ulnar duplication. Neither had facial anomalies and family histories were unremarkable. We suggest that these boys have segmental Laurin–Sandrow syndrome, or mirror‐image duplication, due to somatic mutation involving precursor cells of the left upper limb and that the facial and digital abnormalities in Laurin–Sandrow syndrome are consistent with ectopic anterior hedgehog signaling in the developing limb bud and in the maxillary processes of the face, which closely resemble findings in the Doublefoot (Dbf) mouse mutant.