All people with<unk>  have, at least one, abnormal wrist bone, which can often only be detected by X-ray. Other bone abnormalities are associated with the syndrome. These vary widely in severity, and include a missing thumb, a thumb that looks like a finger, upper arm bones of unequal length or underdeveloped, partial or complete absence of bones in the forearm, and abnormalities in the collar bone or shoulder blade. Bone abnormalities may affect only one side of the body or both sides; if both sides are affected differently, the left side is usually affected more severely. About 75 percent of individuals with<unk>  also have congenital heart problems, with the most common being defects in the tissue wall between the upper chambers of the heart (atrial septal defect) or the lower chambers of the heart (ventricular septal defect). People with<unk>  may also have cardiac conduction disease, or abnormalities in the electrical system that coordinates contractions of the heart chambers. Cardiac conduction disease can lead to slow heart rate (bradycardia); rapid, ineffective contraction of the heart muscles (fibrillation); and heart block. People with<unk>  may have only congenital heart defects, only cardiac conduction disease, both or neither.
Holt–Oram syndrome
Smith–Magenis syndrome
Marshall–Smith syndrome
Laron syndrome
Hanhart syndrome
Ring chromosome 20 syndrome
Wilson–Turner syndrome
Turner syndrome