Ring chromosome 6: Clinical and cytogenetic behaviour

Paz‐y‐Miño, César; Benı́tez, Javier; Ayuso, Carmen; Sanchezcascos, A

doi:10.1002/ajmg.1320350407

Cited by 17 publications

(12 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Available cytogenetic studies on parents of ring 6 probands indicate that the rings result from de novo breakage‐fusion events. In the 23 ring 6 cases, mosaicism for a normal (46,XX or XY) cell line and one or more abnormal cell lines was detected in eight patients indicating post‐zygotic chromosome breakage‐fusion events [Table I; Moore et al, 1973; Kini et al, 1979; Peeden et al, 1983; Levin et al, 1986; Fryns et al, 1990; Paz‐y‐Mino et al, 1990; Birnbacher et al, 2001]. The true frequency of mosiacism is unknown as incomplete examination of tissues probably leads to underascertainment.…”

Section: Discussionmentioning

confidence: 99%

FOXC1 gene deletion is associated with eye anomalies in ring chromosome 6

Zhang

Wang

et al. 2003

American J of Med Genetics Pt A

View full text Add to dashboard Cite

We report a case of ring chromosome 6 presenting with growth and mental retardation, cerebral dysgenesis, eye malformations, mixed hearing loss, and abnormal physical features. Fluorescent in situ hybridization (FISH) and microsatellite genotyping demonstrated segmental deletions of less than 6 Mb on 6p and 1-2 Mb on 6q. The primary karyotype is designated as 46,XY,r(6)(p25q27).ish r(6)(p25.1q27)(D6S344-, FOXC1-, D6S1574+, D6S281-, D6S297+). Secondary structural and numerical variants of the ring 6 were observed in 16% of the cells analyzed. Intragenic genotyping revealed deletion of the paternal FOXC1 gene, haploinsufficiency of which has been reported to cause eye anterior chamber developmental defects. Accordingly, we propose that our patient's ophthalmologic abnormalities result from haploinsufficiency of the transcription factor FOXC1. We present clinical and cytogenetic summaries on 23 reported cases of ring 6 and categorize them into mild, moderate, and severely affected groups. Further phenotype comparisons between cases with ring 6 and cases with only 6p or 6q terminal deletions suggest that genes important for hearing, vision, and central nervous system development remain to be identified in chromosome 6 terminal regions. Molecular definition of the fusion points and tissue mosaicism studies are necessary to better understand the genotype-phenotype correlation of ring 6. We recommend ophthalmology, audiology, cardiology, and central nervous system examinations be part of the routine evaluation for children with a ring chromosome 6.

show abstract

Section: Discussionmentioning

confidence: 99%

FOXC1 gene deletion is associated with eye anomalies in ring chromosome 6

Zhang

Wang

et al. 2003

American J of Med Genetics Pt A

View full text Add to dashboard Cite

show abstract

“…No 6p deletions were recorded. Seizures occurred in four of 15 patients with ring chromosome 6, an uncommon anomaly (88)(89)(90). Details of the seizures and EEG were not given.…”

Section: Other Chromosome 6 Anomaliesmentioning

confidence: 99%

Chromosomal Abnormalities and Epilepsy: A Review for Clinicians and Gene Hunters

et al. 2002

View full text Add to dashboard Cite

Summary:Purpose: We analyzed databases on chromosomal anomalies and epilepsy to identify chromosomal regions where abnormalities are associated with clinically recognizable epilepsy syndromes. The expectation was that these regions could then be offered as targets in the search for epilepsy genes.Methods: The cytogenetic program of the Oxford Medical Database, and the PubMed database were used to identify chromosomal aberrations associated with seizures and/or EEG abnormalities. The literature on selected small anomalies thus identified was reviewed from a clinical and electroencephalographic viewpoint, to classify the seizures and syndromes according to the current International League Against Epilepsy (ILAE) classification.Results: There were 400 different chromosomal imbalances described with seizures or EEG abnormalities. Eight chromosomal disorders had a high association with epilepsy. These comprised: the Wolf-Hirschhorn (4p-) syndrome, MillerDieker syndrome (del 17p13.3), Angelman syndrome (del 15q11-q13), the inversion duplication 15 syndrome, terminal deletions of chromosome 1q and 1p, and ring chromosomes 14 and 20. Many other segments had a weaker association with seizures. The poor quality of description of the epileptology in many reports thwarted an attempt to make precise karyotypephenotype correlations.Conclusions: We identified certain chromosomal regions where aberrations had an evident association with seizures, and these regions may be useful targets for gene hunters. New correlations with specific epilepsy syndromes were not revealed. Clinicians should continue to search for small chromosomal abnormalities associated with specific epilepsy syndromes that could provide important clues for finding epilepsy genes, and the epileptology should be rigorously characterized.

show abstract

“…Due to the circular nature of the affected chromosomes, they tend to be unstable during cell division [ 4 ]. Sister chromatid exchanges due to cell mistakes during mitosis can result in chromosomal abnormalities that produce dicentric rings, interlocked rings, or ring loss leading to monosomy or mosaicism [ 4 , 5 ]. Furthermore, transmission of unstable rings can lead to de novo ring formations in the next generation [ 2 , 3 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Ring chromosome 15 – cytogenetics and mapping arrays: a case report and review of the literature

et al. 2018

Self Cite

View full text Add to dashboard Cite

BackgroundRing chromosome 15 has been associated in previous studies with different clinical characteristic such as cardiac problems, digit and musculoskeletal abnormalities, and mental and motor problems among others. Only 97 clinical cases of ring chromosome 15 syndrome have been reported since 1966 and a common phenotype for these patients has not been established.Case presentationThe present case report describes a 15-month-old girl from the Amazon region of Ecuador, of Mestizo ancestry, who after cytogenetic tests showed a 46,XX,r(15) karyotype in more than 70% of metaphases observed. Her parents were healthy and non-related. The pregnancy was complicated and was positive for intrauterine growth retardation. Her birth weight was 1950 g, her length was 43.5 cm, and she had a head circumference of 29.3. In addition to postnatal growth delay, she had scant frontal hair, small eyes, hypertelorism, low-set of ears, flattened nasal bridge, anteverted nostrils, down-turned mouth, three café au lait spots, and delayed dentition.ConclusionsDespite the frequency of some phenotypes expressed in the different clinical cases reviewed and the present case, a common phenotype for patients with ring 15 could not be determined and it is restricted to the region of the chromosome lost during the ring formation.

show abstract

Ring chromosome 6: Clinical and cytogenetic behaviour

Cited by 17 publications

References 10 publications

FOXC1 gene deletion is associated with eye anomalies in ring chromosome 6

FOXC1 gene deletion is associated with eye anomalies in ring chromosome 6

Chromosomal Abnormalities and Epilepsy: A Review for Clinicians and Gene Hunters

Ring chromosome 15 – cytogenetics and mapping arrays: a case report and review of the literature

Contact Info

Product

Resources

About