Learn more about the syndrome at the epilepsy foundation today. Ring chromosome 20 is a genetic syndrome characterized by a childhood or adolescentonset epileptic encephalopathy in a previously developmentally normal child. Depending on the amount of chromosomal loss and associated mosaicism. Ring chromosome 20 syndrome rc20 is one of a number of chromosomal disorders associated with difficult to control epilepsy. An association between the hypomelanosis of ito and ring chromosome 20 syndrome was never reported peviously. Patients with partial deletion of a d chromosome, 122 including those with a ring d chromosome, 1,2,47,10,15,1719,22 present a variety of clinical findings. Apr 11, 2017 ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues. Autosomal ring chromosomes in human genetic disorders. Department of clinical genetics, university hospital, se221 85, lund, sweden december 2001 chromosomes are often regarded merely as static containers for genetic information. People with ring chromosome 20 syndrome have one copy of this abnormal chromosome in some or all of their cells. Chromosome 21 ring is a rare chromosomal disorder in which the affected infant has a breakage of chromosome 21 at both ends, and the ends of the chromosome join together to form a ring. Ring chromosome 20 r20 syndrome is characterized by mild to moderate mental.
We will be providing unlimited waivers of publication charges for accepted articles related to covid19. Ring chromosome 20 epilepsy syndrome in children neurology. Ring chromosome 14 syndrome is almost never inherited. Chromosomes are very important structures within each cell in the body, which hold our genetic material. A proportion of mitoses presented a double ring 20 or a monosomy. They are heterogeneous with variable size and genetic content and can originate from any chromosome. Consequently, we consider that clinical features of ring chromosome 20 syndrome are caused essentially by the loss of the ring chromosome 20 involving mosaic chromosome 20 monosomy and not because the mere deletion of the two epilepsyassociated genes chrna4 and kcnq2 located at 20q. A ring chromosome typically occurs as a random event during the formation of reproductive cells eggs or sperm or in early embryonic development.
An analysis of these cases together with those in the literature indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of. Ring chromosome 20 genetic and rare diseases information. Ring chromosome 20 is a genetic disorder characterized by intractable epilepsy, behavioral problems, and cognitive deficit. Aug 20, 2011 ring f chromosome mosaicism 46, xy, 20r46, xy in an epileptic child without apparent hematological disease. Sep 25, 2001 article abstract ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of nonconvulsive status epilepticus. Ring f chromosome mosaicism 46, xy, 20r46, xy in an epileptic child without apparent hematological disease. People with ring chromosome 20 often have recurrent seizures or epilepsy. Ring chromosome 20 is a chromosome abnormality that affects the development and function of the brain. Ezogabine is the first potassium channel opener marketed in the united states. The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience of health. Some ring chromosomes, including ring 14, 17, and 20, are strongly associated with seizure disorders. Table of contents case reports in genetics hindawi. Ring chromosome 20 is a rare chromosomal disorder characterized by severe, refractory epilepsy, cognitive delay, and unspecific dysmorphic traits. Ring chromosome 20, ringshaped chromosome 20 or r20 syndrome is a rare human.
Contribution of array cgh in prognosis and genetic. We are committed to sharing findings related to covid19 as quickly and safely as possible. Ring chromosome 20, ringshaped chromosome 20 or r20 syndrome is a rare human chromosome abnormality where the two arms of chromosome 20 fuse to form a ring chromosome. Six cases of epilepsy associated with ring chromosome 20 are presented. Cognitive impairment and abnormal behaviour related to. Ring chromosome 20 syndrome, also known as r20, is a rare chromosomal anomaly resulting from a break on each arm of chromosome 20 resulting in ring formation. Therefore, precisely matching the physical sequence to the designed sequence is crucial for verification of the design principles in genome synthesis. The ring chromosome 20 foundation was created to provide information, resources and assistance to families affected by ring chromosome 20 syndrome. An analysis of these cases together with those in the literature indicates that the syndrome forms a continuous spectrum, and no further taxonomic subdivision is possible at this stage of knowledge. Therefore, the severity and symptoms associated with ring chromosome 9 vary from person to person. Patients with partial deletion of a d chromosome,122 including those with a ring d chromosome,1,2,47,10,15,1719,22 present a variety of clinical findings. We have identified a partial deletion of the short arm of chromosome 20 in a 5yearold boy from parents having normal phenotype and karyotype. A ring chromosome is an aberrant chromosome whose ends have fused together to form a ring. Molecular analysis of ring chromosome 20 syndrome reveals.
It is one of the more commonly seen ring chromosomes. Ring chromosome 14 syndrome is a rare chromosomal disorder characterized by early onset refractory epilepsy, intellectual disability, autism spectrum disorder and a number of diverse health issues. Media in category ring chromosome 20 syndrome this category contains only the following file. Group 2 n7 had nonmosaic ring chromosomes with a deletion at one or both ends of the chromosome, near the ring fusion point. Ring chromosome 9 is a very rare chromosome abnormality in which the ends of chromosome 9 join together to form a ring shape.
Ring chromosome 20 and nonconvulsive status epilepticus. A ring chromosome is a circular structure that occurs when a chromosome breaks in two places and its broken ends fuse together. Ring chromosomes were first discovered by lilian vaughan morgan in 1926. Our hope is to share as much information as possible so that medical professionals, physicians, and families can. The form of and ring chromosome depending on the size and the amount of the formation is the occurrence of a break in both arms. People with ring chromosome 14 syndrome have one copy of this abnormal chromosome in some or all of their cells. Ring chromosomes are usually formed by fusion of the deleted telomere ends of both chromosome arms. Ring chromosome 20 syndrome is a rare chromosomal disorder characterized by refractory epilepsy, with seizures in wakefulness and sleep, behavioral problems and mild to severe cognitive impairment.
Ring 20 syndrome is a very rare condition in which one of the two copies of chromosome 20 has formed a ring rather than the typical linear chromosome. Read new association between ring chromosome 20 syndrome and hypomelanosis of ito, pediatric neurology on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The remaining 25% presented two normal chromosomes chromosome 20. May 29, 2018 ring chromosome 9 is a very rare chromosome abnormality in which the ends of chromosome 9 join together to form a ring shape. Ring chromosome 20 syndrome is marked by a characteristic seizure phenotype. Electroclinical evolution in ring chromosome 20 epilepsy. Molecular analysis of ring chromosome 20 syndrome reveals two. Ring chromosomes involving both the autosomes and the sex chromosomes have been described pezzolo et al.
The clinical limits of this syndrome can now be defined. On the other hand, 90 percent of these cases are of maternal origin. A study of the ring chromosome syndrome is presented with detailed clinical and cytogenetic features of three new unrelated cases. Ring 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. Cognitive impairment and abnormal behaviour related to ring. Pdf psychosis and epilepsy in ring chromosome 20 syndrome. Pdf rare epileptic syndrome of ring chromosome 20 with epileptic.
The syndrome is associated with epileptic seizures, behaviour disorders and mental retardation when not all cells contain a ring chromosome 20, the individual suffers from ring 20 chromosomal mosaicism. Ring chromosome 20 r20 is a rare chromosomal disorder, first characterised as a. Of interest is ring chromosome 20 which has a significant association with epilepsy with seizure onset in early childhood. The ssmc was characterized by various molecular cytogenetic techniques and.
Article pdf available in journal of the medical association of. Facial dysmorphism or other congenital malformations are rarely reported making it difficult to diagnose the syndrome based on clinical findings alone. Guideline recommendations for diagnosis and clinical. Abstract we present the clinical, electroencephalographic, neuroimaging brain magnetic resonance image mri and spectroscopy by mri and cytogenetic findings of a young male patient with a rare cytogenetic.
Contribution of array cgh in prognosis and genetic counselling of prenatally diagnosed supernumerary ring chromosome 20. Ring chromosome 20 syndrome is caused by a chromosomal abnormality known as a ring chromosome 20 or r20. Ring chromosome 20 r20 syndrome is a rare disease characterized by refractory epilepsy, mild to moderate mental retardation, facial dysmorphism and particular electroencephalographic disorder with nonconvulsive status epilepticus. The authors findings in four children, all without dysmorphic features, indicate that mental deterioration and frequent subtle nocturnal frontal lobe seizures, associated with a characteristic. Methods to understand the structure and composition of the ring chromosome 20 r 20 in this patient cohort, blood specimens from 28 affected individuals were analysed by. The syndrome is associated with epileptic seizures, behaviour disorders and mental retardation.
Ring chromosome 14 syndrome genetics home reference nih. Ring chromosome 20 syndrome is a rare chromosomal disorder characterized by refractory epilepsy, with seizures in. Ring chromosomes, which usually involve gene copy nu. Ring chromosome 20 is caused by an abnormal chromosome known as a ring chromosome 20 or r 20.
Ring chromosome 20 syndrome is caused by a chromosomal abnormality known as a ring chromosome 20 or r 20. Ring chromosome 20, ring shaped chromosome 20 or r 20 syndrome is a rare human chromosome abnormality where the two arms of chromosome 20 fuse to form a ring chromosome. Ring 20 chromosomes can also form from two breaks, one in the short p arm, usually in the region known as 20p, and one in the long q arm, usually in the region known as 20q. The incidence has been estimated at 1 in prenatal samples. Other symptoms might include intellectual disability, behavioral difficulties, growth delay, short stature, a small head microcephaly, and characteristic facial features ring chromosome 20 is caused by an. When this occurs, the chromosome ends can stabilise themselves by fusing to produce a ring. The study of these cases and 20 cases reported in the literature revealed tha. The amount of genetic material lost at the two ends of the chromosome may vary. Ring chromosome 20 syndrome without deletions of the. The aim of this work is to provide recommendations for the diagnosis and management of persons affected by ring chromosome 14 syndrome based on evidence from literature and experience.
The potassium channelcoding gene kcnq2 is localized at the locus q. The resulting ring may be missing genes, or it may contain extra copies of genes. Chromosome 21 ring nord national organization for rare. Enable javascript to view the expandcollapse boxes. Ring chromosome 17 not involving the millerdieker region. Jan 26, 2016 ring chromosome 20 is caused by an abnormal chromosome known as a ring chromosome 20 or r 20. The nonmosaic nature of these rings is consistent with a meiotic origin. 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. Ring chromosome 14 syndrome is caused by a chromosomal abnormality known as a ring chromosome 14, sometimes written as r14.
Disorders arising from the formation of a ring chromosome include ring chromosome 20 syndrome where a ring formed by one copy of chromosome 20 is associated with epilepsy. A ring chromosome is denoted by the symbol r in human genetics and r in drosophila genetics. Seizures are a major symptom of what is known as ring chromosome 20 syndrome. Our hope is to share as much information as possible so that medical professionals, physicians, and families can better understand the syndrome and its treatment. Jan 30, 2015 phenotypes associated with ring chromosomes are highly variable as apart from any deletion caused by ring formation, imbalances from ring instability can also occur. Genetic investigations on 8 patients affected by ring 20 chromosome. Perfect designer chromosome v and behavior of a ring. In some cases, the ring chromosome is present in only some of a persons cells. Ring chromosome 15 cytogenetics and mapping arrays. We present a case of mosaic ssmc diagnosed prenatally after amniocentesis. On the other hand, abnormalities patients with ring chromosomes often exhibit a and consequently infertility in affected men 1, 2.
Ring chromosomes can extend those design principles to provide a model for genomic rearrangement, ring chromosome evolution, and human ring chromosome disorders. Phenotypes associated with ring chromosomes are highly variable as apart from any deletion caused by ring formation, imbalances from ring instability can also occur. Clinical findings in a patient mosaic for a supernumerary ring chromosome 20 enrique daniel austinward, 1 silvia castillo, yuri dragnic,2 patricia sanz, samuel salazar,1 and joan h. The study of these cases and 20 cases reported in the literature revealed that they constitute a distinct epileptic syndrome. Ring chromosomes may form in cells following genetic damage by mutagens like radiation, but they may also arise spontaneously during. Article abstract ring chromosome 20 mosaicism is associated with dysmorphic features, mental retardation, and intractable seizures, including recurrent episodes of nonconvulsive status epilepticus. Background the ring chromosome 20 syndrome r20 is a rare genetic disorder associated with a refractory electroclinical epilepsy syndrome and variably expressed comorbidities of intellectual disability and dysmorphism. Ring chromosome 20 syndrome genetics home reference nih. The authors findings in four children, all without dysmorphic features, indicate that mental deterioration and frequent subtle nocturnal frontal lobe seizures, associated with a. Marleide da mota gomes 1, irene lucca 2, sonia alonso monteiro bezerra 2, juan llerena jr 3, denise madeira moreira 1. Cytogenetic investigation in both parents revealed a normal karyotype. Ring chromosomes arise following breakage and rejoining in both chromosome arms. Ring chromosome 9 genetic and rare diseases information.
There are several different forms of the r 20 syndrome, with potential differences among. Ring chromosome 20 syndrome, also known as r 20, is a rare chromosomal anomaly resulting from a break on each arm of chromosome 20 resulting in ring formation. It is due to an abnormality in chromosome number 20. Ring chromosome 20 r20 is a rare condition and one that often causes epilepsy in children. Molecular analysis of ring chromosome 20 syndrome reveals two distinct groups of patients. Clinical findings in a patient mosaic for a supernumerary. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Methods to understand the structure and composition of the ring chromosome 20 r20 in this patient cohort, blood specimens from 28 affected individuals were analysed by. The ring chromosome showed restoration of subtelomeric gene expression levels. Ring chromosome 20 syndrome genetics home reference.
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