Trisomy 7p resulting from 7p15;9p24 translocation: report of a new case and review of associated medical complications

Abstract

The authors report on a young girl with generalized developmental deficits originally thought to be caused by an unusual reaction to DPT vaccination. At the age of 4(1/2) years, chromosome analysis showed that the terminus of the short arm of chromosome 9 had extra material believed to originate from 7p terminus, thus she was considered to be trisomic for a segment of 7p and monosomic for a small portion of 9p [46,XX,der (9), t(7;9)(p15;p24)]. Ten years later, molecular cytogenetic testing using fluorescence in situ hybridization (FISH) confirmed that the extra chromosomal material represented partial trisomy 7p. The proposita had a high and large forehead, hypertelorism, and broad nasal bridge, findings seen in most individuals with trisomy 7p. Long-term follow-up showed the presence of hypothyroidism, obesity, and cerebral palsy. A review of all published cases of trisomy 7p with focus on associated complications suggests a well-defined pattern of abnormalities characterized by musculoskeletal, cardiovascular, neurological, genital, and ocular abnormalities in decreasing frequency. At least one-third of affected individuals died in infancy and close to half had severe mental retardation. FISH was essential in the confirmation of the cytogenetic abnormality and further delineation of the chromosomal disorder.