[Hereditary transmission of a familial chromosome marker (author's transl)].

Banding patterns allow identification of chromosome 22 admitting today trisomy 22 without doubt. A case of this chromosomic aberration is presented. Particular characteristic of the case is the existence of Gp+ chromosome in the mother, two of her brothers and two later brothers of the "probandus". This variation is not discussed as origin of the trisomy.