total absence of the thumb may be an isolated anomaly, but it is often associated with some other congenital malformation;
absent thumb may be inherited as autosomal dominant or may be sporadic;
absent thumb is frequently observed in Holt-Oram syndrome, Fanconi's anemia, and ring D chromosome abnormalities;
absent radius is almost always associated with an absent thumb, except in thrombocytopenia radial aplasia (Fanconi's syndrome), where thumb is present even when the radius is absent; (see radial club hand);
Radiographs
Treatment
treatment in most cases of absent thumb is to perform pollicization of the index finger;
this will have the most significant effect on handling large objects;
patients with an isolated hypoplasia of the thumb tend to do better with pollicization than do patients with associated radial aplasia
