Ring chromosome 6: Case report and review

Nishi, Yoshikazu; Yoshimura, Osamu; Ohama, Koso; Usui, Tateo

doi:10.1002/ajmg.1320120115

Cited by 30 publications

(31 citation statements)

References 8 publications

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“…In some cases, single cells carrying rings with two or more centromeric regions have been described (Zuffardi et al, 1980;Nishi et al, 1982). Henegariu et al (1997) described a patient with different polycentric ring chromosomes of the same origin.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the first supernumerary tricentric ring chromosome 1 mosaicism by conventional and molecular cytogenetic techniques

Tönnies

Hennies

Spohr³

et al. 2003

Cytogenet Genome Res

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We report on the conventional cytogenetic and fluorescence in situ hybridization (FISH) results obtained for a 3.5-year-old girl with developmental and language delay and a supernumerary ring chromosome mosaicism in 8% of T-lymphocytes analyzed. Using different conventional and molecular cytogenetic techniques as YAC hybridization and comparative genomic hybridization, we could show that the extra tricentric ring chromosome consists of three heterochromatic blocks with inserted euchromatic material. Additionally, chromosome microdissection followed by FISH analysis demonstrated that the small tricentric ring chromosome consisted of material from the pericentromeric region of chromosome 1q21. Thus, the patient has a mosaic of normal cells and cells with partial pentasomy of the pericentromeric region of chromosome 1. So far, 19 cases with single supernumerary marker chromosome 1 have been published, but no tricentric ring chromosome 1 is, to our knowledge, reviewed in the literature. In this study, we compare the clinical features of our patient with cytogenetically comparable cases described in the literature. We introduce a hypothesis for the formation of a tricentric ring chromosome: starting with a monocentric ring, sister chromatid exchange leading to the formation of a tetracentric ring, which underwent intrastrand recombination generating the tricentric ring.

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Section: Discussionmentioning

confidence: 99%

Characterization of the first supernumerary tricentric ring chromosome 1 mosaicism by conventional and molecular cytogenetic techniques

Tönnies

Hennies

Spohr³

et al. 2003

Cytogenet Genome Res

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show abstract

“…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.…”

Section: Discussionmentioning

confidence: 91%

Prenatal Diagnosis of Ring Chromosome 6 in a Fetus With Hydrocephalus

et al. 1996

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“…However, his delayed growth was not necessarily the result of the r(6), because there was``a striking familial tendency to short stature'' [Carnevale et al, 1979]. Another mentally normal child, a girl described by Nishi et al [1982] and later again by Yoshimitsu et al [1987], was also karyotyped because of her short stature (À4.6 SD at three years). This``pleasant girl with a normal facial appearance, normal eyes, nose, mouth, and ears'' had an IQ of 92 and``was attending a regular school, and her school record was normal'' [Nishi et al, 1982].…”

Section: Mental Retardationmentioning

confidence: 92%

Ring chromosome 6 in three fetuses: Case reports, literature review, and implications for prenatal diagnosis

et al. 2002

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Prenatal and postnatal findings in three fetuses with a ring chromosome 6 are presented, and the literature of this rare cytogenetic disorder is reviewed. The described fetuses illustrate the broad spectrum of the clinical manifestation of ring chromosome 6. In one fetus, the disorder was diagnosed incidentally by a routine amniocentesis due to advanced maternal age. The other two fetuses were hydrocephalic and had other congenital anomalies. Remarkably, the ring chromosome 6 tends to disappear in cultured amniotic fluid cells; karyotyping revealed complete or nearly complete monosomy 6. In contrast, the ring was preserved in high proportions of fetal leukocytes. Postnatal growth retardation is the only consistent finding of this chromosomal disorder. Maternal age is not significantly above average. An additional review of 20 literature cases revealed a striking tendency to hydrocephalus, either due to deficient brain growth or secondary to an aqueductal stenosis. Children with hydrocephalus and ring chromosme 6 tend to display facial dysmorphism and may have additional malformations, growth failure, eye anomalies, and seizures. In contrast, there are two reports on children with a ring chromosome 6 who had short stature, normal appearance, and a normal or almost-normal psychomotor development. In such patients at the mild end of the clinical spectrum, the phenotype is basically restricted to what Kosztolányi. [1987: Hum Genet 75:174-179] delineated as "ring syndrome," comprising "severe growth failure without major malformations, without a specific deletion syndrome, with only a few or no minor anomalies, and mild to moderate mental retardation." This "ring syndrome" is considered to occur independently of the autosome involved in the ring formation. The overall impression from our cases and from the literature review of cases with ring chromosome 6 is that the karyotype-genotype correlation is poor. This makes prognostic counseling of parents difficult and unsatisfactory. Serial targeted ultrasound examinations, especially of the brain, are decisive factors in elucidating the prognosis.

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Ring chromosome 6: Case report and review

Cited by 30 publications

References 8 publications

Characterization of the first supernumerary tricentric ring chromosome 1 mosaicism by conventional and molecular cytogenetic techniques

Characterization of the first supernumerary tricentric ring chromosome 1 mosaicism by conventional and molecular cytogenetic techniques

Prenatal Diagnosis of Ring Chromosome 6 in a Fetus With Hydrocephalus

Ring chromosome 6 in three fetuses: Case reports, literature review, and implications for prenatal diagnosis

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