Ring chromosome 6: Report of a patient and literature review

Abstract

A patient with ring chromosome 6 had most of the manifestations previously reported in this syndrome and also had albinoid fundi and unilateral aniridia, findings not previously described. In most peripheral leukocyte metaphases analyzed, one chromosome 6 was replaced by a monocentric ring chromosome with deletion of the 6p and 6q. Fifteen other patients with a ring chromosome 6 have been reported. The most frequent findings were mental retardation, prenatal and postnatal failure, epicanthal folds, flat nasal bridge, short neck, apparently low-set and/or malformed ears, microphthalmia, and micrognathia. Studies of coagulation Factors XII and XIII and of the P blood group for possible assignment on distal 6p and 6q did not provide evidence for localization of the genes for these factors on the pter----p24 part of chromosome 6.

Ring chromosome instability evaluation in six patients with autosomal rings

“…We found that the cells showing ring chromosome instability can vary among different ring chromosomes (4, 14, 15, and 18) and even when the ring chromosome is the same, as shown by our three ring 14 cases, a finding also reported by Chitayat et al (1987).…”

Prenatal Diagnosis of Ring Chromosome 6 in a Fetus With Hydrocephalus

“…Only 18 cases have been described in the literature (Moore et al, 1973;Van den Berghe et al, 1974;Fried et al, 1975;Salamanca-Gomez et al, 1975;Wurster-Hill and Hoefnagel, 1975;Sele et al, 1977;Kini et al, 1979;Carnevale et al, 1979;Cruz-Martin et al, 1980;Nishi et al, 1982;Peeden et al, 1983;Levin et al, 1986;Chitayat et al, 1987;Romke et al, 1987;Paz-y-Mino et al, 1990). Most patients with ring chromosome 6 have associated multiple anomalies.…”

“…There does not appear to be a characteristic phenotype for this chromosome disorder, but the most common clinical features are mental retardation, microcephaly, micrognathia, intrauterine growth retardation, low-set ears, hypertelorism, and short stature (Schinzel, 1994). Hydrocephalus or ventriculomegaly has been described in six cases (Peeden et al, 1983;Levin et al, 1986;Chitayat et al, 1987). Hydrocephalus has also been reported in patients with terminal deletions of chromosome 6q (Shen-Schwartz el al., 1989) and chromosome 6p (Reid et al, 1983;Palmer et al, 1990).…”

Distal deletion of the short arm of chromosome 6

“…However, in contrast to patients with del(6p) and r(6), patients with monosomy 6q have not been reported as having congenital eye malformations. Table I1 presents in detail the eye findings in patients with distal del(6p), distal del(6q) [Stevens et al, 19881, and r(6) [Carnevale et al, 1979;Chitayat et al, 1987;Cruz-Marin et al, 1980;Fried et al, 1975;Kini et al, 1979;Levin et al, 1986;Nishi et al, 1982;Peeden et al, 1983;Salamanca-Gomez et al, 1975;Sele et al, 1977;Van den Berghe et al, 19741. Table I1 includes only patients whose reports included formal eye examinations.…”