Condition	Limb abnormalities	Other characteristics
Fanconi anemia	Thumb and/or radial deformities	Bone marrow suppression and pancytopenia; developmental delays; skin, gastrointestinal tract, and genitourinary abnormalities; high risk of malignancies
Holt-Oram syndrome	Upper limb malformations; absent or malformed thumb (triphalangeal thumb)	Cardiac abnormalities, including atrial and ventricular septal defects
Roberts syndrome	Bilateral hypomelia or tetraphocomelia with upper limbs typically more severely affected than lower limbs; thumb aplasia or hypoplasia	Intrauterine growth retardation, craniofacial abnormalities
Thrombocytopenia–absent radius syndrome	Absent radius with normal thumbs	Thrombocytopenia, cow's milk allergy, cardiac and genitourinary abnormalities
VACTERL association	Typically abnormalities of the thumb and radius; thumb is often absent	Anomalies of the skeleton, heart, and genitourinary system can occur