THE 7p PARTIAL TRISOMY SYNDROME

Abstract

Various partial trisomy syndromes have been described since the advent of the chromosome banding techniques. However, a documented case of partial trisomy 7p has, aa yet, not been reported. We have recently detected this aberration in a four month old female infant who presented with the following anomalies: asymmetric cranium with widely patent anterior fontanelle and netopic suture, deep widow's peak, hypertelorism, bilateral choanal atreaia, prominent nasal bone, low set, rotated ears, maxillary hypoplasia, high arched palate, micrognathia, arachnodactyly with contractures of the interphalangeal joints, congenitally dislocated hip, and vertical talus. The patient's banded karyotype revealed a 46, XX, 5p+ complement. With G, Q, and R banding, a 46, XY, t(5;7)(p15;p15) karyotype was found in the father. Studies on the mother were normal. Therefore, it is evident that the patient is trisomic for the distal short arm of chromosome 7: 46, XX, -5, +der (5), t(5;7) (5qter→5p15::7p15→7pter) pat. The finding of this translocation will allow us to diagnose an affected child prenatally with amniocentesis in the subsequent pregnancies of this couple and in those of other translocation carriers in the paternal family. Of further interest is the potential for using this translocation for regional gene mapping of genes known to be on chromosome 7 both by dosage effect and by somatic cell hybridization.