Definition

Holt-Oram syndrome (HOS) is one of several hereditary conditions characterized by abnormalities of the heart and hands at birth.

Description

HOS involves variable abnormalities of the heart and the hands, or hands and arms. The heart abnormalities may range from disturbances in the electrical conduction pattern of the heart to severe structural defects requiring surgical intervention for survival. The abnormalities of the upper limbs are usually bilateral (occurring on both sides) and asymmetric (not identical from side to side). The severity of the upper limb changes may range from minor signs, such as clinodactyly (inward curvature of the fingers) to disabling defects, such as small or missing bones resulting in very short arms.

Some individuals with HOS are so mildly...