Partial 3p trisomy and different rearrangements involving chromosome 3 in the proposita's family

Abstract

A case of partial 3p trisomy is reported here. A review of published cases (8 males, 2 females, 7 families) shows a characteristic pattern of anomalies, constituting one more syndrome of multiple congenital anomaly and mental retardation (MCA/MR) characterized by microcephaly, brachycephaly, frontal bossing, temporal identation, square hypertelorism or telecanthus, epicanthus, short nose with a large tip, prominent cheeks, long and protruding philtrum, large and downturned mouth, protruding mid-upper lip, micro- or retrognathia, short neck, congenital heart defects, gastrointestinal malformation, penile hypoplasia, neuromotor or mental retardation, and predominance of whorls on digits. The proposita had a 46,XX,der(11),t(3;11)(p21;q25) karyotype. The mother was carrier of a de novo 3;11 balanced translocation. Chromosome mosaicism was detected in a female sibling of the proposita: 46% of her cells were 46,XX and 54% had 46,22,t(3;20(p21;13) karyotype - ie, a de novo 3;20 balanced translocation. We discuss the origin of this mosaicism and the possible meaning of the breaks involving the same region of chromosome 3 (region 3p 21) in the members of the proposita's family.