RESUMEN
Congenital hypoplasia of thumb is rare malformation which is less likely to appear as an isolated entity. Four independent subjects exhibiting various grades of underdeveloped first digital ray were recruited. The affected autopods had narrow palms, medial or valgus inclinations of index fingers and thenar weakness, while the postaxial digits were least affected. According to the classification of hypoplastic thumb by Blauth and Schneider-Sickert (1981), the phenotypes were concordant with types 3 and 4. In one of the subjects there was contralateral preaxial polydactyly. All cases were sporadic and nonsyndromic and parental consanguinity was witnessed in two individuals. Recurrent appearance of similar phenotypes may suggest genetic etiologies which should be elucidated with the help of high-throughput genetic methods.