Congenital anomalies account for the majority of cases.
Deficiencies may be partial or total. There is no pattern or proven cause to most deficiencies though a very small number of drugs, such as thalidomide, have a proven link. There are also specific syndromes which include arm defects amongst their characteristic features. Inheritance patterns Most arm and hand deficiencies are sporadic events. In TAR Syndrome inheritance is autosomal recessive.