Chromosome 3 Duplication q/Deletion p Syndrome

This report describes the clinical, chromosomal, and radiological findings in four unrelated families with different recombinant chromosome 3 abnormalities. On the basis of the phenotypic and cytogenetic findings seen in our six patients and those noted in two recent reports, we concur with Allderdice et al. that the syndrome in which the long arm (q) of chromosome 3 is duplicated and the short arm (p) is deleted is a distinct clinical entity. The psychomotor retardation found in this syndrome appears to be caused mostly by monosomy of the region 3pter→3p25, while severity of the physical malformations (and hence the lethality) is apparently proportional to the amount of extra chromosome 3q material present. That is, patients who are trisomic for larger segments are physically more affected than patients who are trisomic for smaller amounts of the long arm of chromosome 3. Features common to the chromosome 3 duplication q/deletion p syndrome are mental and growth retardation, microcephaly, seizures, prominent and/or asymmetric frontal bossing, ocular hypertelorism, ptosis, upward-slanting palpebral fissures, and low-set and/or malformed ears. Other anomalies frequently seen are short webbed neck, various types of congenital cardiovascular disorders, omphalocele, cryptorchidism, spina bifida, short digits, hypotonia, and digital impressions on skull x-ray examination which are presumably caused by trisomy for the distal band (3q28) of the long arm of chromosome 3. In addition, the importance of doing chromosome studies in persons who are mildly affected, both mentally and physically, is illustrated by the study of one of these families.