Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We report on a 14-year-old boy with ring chromosome 20. Clinical manifestations included postnatal growth retardation, epilepsy, microcephaly, behaviour disorder, minor facial anomalies, small sella turcica, possible partial growth hormone deficiency, and mental retardation. A decreased activity of enzyme carboxypeptidase-L/protective protein (CP/PP) in cultured fibroblasts was demonstrated in our patient and a patient with a karyotype 46,XY,-14, + der(14)t(14;20)(14pter----14q32.3::20q13.1----20qter)m at. This suggests possible assignment of the CP/PP gene to the distal segment of 20q.
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PMID:Ring chromosome 20 and possible assignment of the structural gene encoding human carboxypeptidase-L to the distal segment of the long arm of chromosome 20. 160 51

Ring (20) chromosomal mosaicism defined by two cell lines (one normal and the other with the ring) has been demonstrated in lymphocyte and fibroblast cultures from three members of a family through two generations. Two carriers of the ring chromosome were affected and showed the typical signs of r(20) syndrome including mental retardation, microcephaly, behavioral disorders, and epilepsy. The epilepsy is characterized by complex partial seizures sometimes evolving secondarily into generalized tonic-clonic seizures and is poorly controlled by or resistant to medical treatment. The mother of the two patients, also a carrier of ring (20) chromosomal mosaicism, was clinically and phenotypically normal and did not exhibit any signs of epilepsy. Lymphocyte and fibroblast cultures from the most severely affected sib, the proband, contained the highest percentage of cells with ring (20) chromosome and revealed the greatest instability of the ring. Though it is assumed that the ring (20) chromosome arose from terminal breakage and reunion in both arms, no loss of genetic material could be documented cytogenetically. Yet the question arises of how ring chromosomal mosaicism can be passed on. One explanation might be that a chromosome 20 predisposed to terminal lesions or breaks is transmitted from the mother to her offspring. Inherited instability of this type might lead to de novo formation of the ring.
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PMID:Familial ring (20) chromosomal mosaicism. 277 54

Intractable epilepsy and peculiar EEG patterns characterize ring chromosome 20 syndrome [r(20)], while dysmorphic features, mental retardation and behavioural disturbances are widely variable. The clinical evolution of r(20) over time is not well defined as relatively few cases have been reported. Here we describe a patient with severe clinical features followed for a 25-year period. The patient was subjected to clinical, psychometric and EEG evaluation twice a year from the age of 21 years. Cytogenetic studies, using chromosome analysis and fluorescence in situ hybridization (FISH) and several immunological investigations were performed. Ring chromosome 20 was found in 50% of examined metaphases with the deletion of subtelomeric regions 20p and 20q. Our patient presented with marked dysmorphic features, severe mental retardation, tetraparesis, dysarthria and intractable epilepsy with onset during the first year of life. During follow up, EEG findings and clinical features progressively worsened: a progressive disorganization of background EEG activity occurred and mental and motor impairment evolved. The severity of clinical expression depended on the extent of chromosomal deletion and on the haploinsufficiency of other important related genetic loci due to ring instability. The progressive worsening of both clinical and EEG features over a long period, which has also been reported by other authors, further characterized this syndrome.
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PMID:Electroclinical evolution in ring chromosome 20 epilepsy syndrome: a case with severe phenotypic features followed for 25 years. 1680 95

Ring chromosome 20 syndrome combines epilepsy with varying levels of mental retardation, behavioral disorders, and malformations. Epilepsy is generally serious, with frequent drug resistance. The pathophysiology of seizures remains unclear. Rearrangements of two epilepsy genes, CHRNA4 and KCNQ2, have been raised as the cause. We report the observation of one child, with a telomeric deletion 20p13, with no epileptic symptoms. Preservation of CHRNA4 and KCNQ2 gene activity could explain this distinctive feature.
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PMID:[Polymorphic expression of epilepsy and cognitive impairment in ring chromosome 20 syndrome]. 2139 68

A case of epilepsy associated with ring chromosome 20 [r(20)] syndrome was first reported in 1972. Relatively few cases of [r(20)] syndrome have been reported. We report here a middle-aged female with this syndrome. She had two types of seizures characterized by complex partial seizure with complex motor automatism mainly occurred while asleep and episodes of fluctuating consciousness (non-convulsive status epilepticus) lasting 40-60 min. The ictal electroencephalography (EEG) findings of the latter showed almost continuous diffuse spike and wave complexes or high voltage slow waves. The interictal EEG findings showed spike or sharp waves located in bilateral frontal regions or 3-6Hz diffuse high voltage slow waves intermingled with spikes in left posterior areas. We reviewed and discussed the characteristics of [r(20)] syndrome reported in the literature, intractable seizures, behavioral problems and some degree of mental retardation or dysmorphism, especially variable EEG findings characterized this syndrome.
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PMID:[A case of epilepsy with ring chromosome 20 syndrome]. 2315 13

The authors report the clinical features, electroencephalography (EEG), neuroimaging (brain magnetic resonance image-MRI), and cytogenetic findings of a young female patient with rare cytogenetic anomalies characterized by de novo 46, XX, r (20) (p13q13.3). The patient had a history of mild mental retardation, emotional liability and intractable epilepsy with non-convulsive status epilepticus. The MRI brain showed focal cerebral dysplasia over the left temporal region. The multiple seizures were refractory to antiepileptic medications and prolonged, confused state with or without a motor component. The continuous video-EEG monitor showed epileptiform discharges over bilateral frontal regions with frontal origin. The symptoms were relieved after midazolam infusion. A patient who was present with intractable epilepsy with continuous frontal epileptiform discharges, mental retardation, abnormal behavior, without dysmorphic features should be suspected of chromosomal abnormalities especially ring chromosome 20.
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PMID:Rare epileptic syndrome of ring chromosome 20 with epileptic encephalopathy: a case report. 2539 Nov 99