[Long-arm deletion of chromosome 1: 46,XY, del (1) (Q42) (author's transl)].

A case of long-arm deletion of chromosome No. 1: 46,XY, del (1) (q42) is reported. From the revised bibliography only two cases are comparable cytogenetically, not so phenotypically. The usefulness of the recent banding techniques in the precise diagnosis of small structural anomalies of the chromosome is outlined and the difficulty in establishing the relationship between chromosomal alteration and phenotypical characters are commented.