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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 7-month-old boy with developmental delay and congenital abnormalities and a 58-year-old man with mental retardation, impaired speech, and dysmorphic features were referred for cytogenetic studies. The peripheral blood chromosome studies of Patient 1 had a de novo mosaic karyotype with 2-6 supernumerary marker chromosomes. Patient 2 had a mosaic karyotype with 1-5 supernumerary marker chromosomes and normal cells. All markers appeared to have a centromere by C-banding and also by fluorescence in situ hybridization (FISH) using all centromere probe for Patient 1. The majority of the markers appeared like rings. Except for one marker in Patient 1 and 2-3 markers in Patient 2 with discernible >5 Mb euchromatin, the rest of the markers were minute and some appeared to have barely discernible euchromatin in C-banding or FISH. Spectral karyotyping (SKY) was attempted to determine the origin of the marker chromosomes. Because some markers had barely any euchromatin, their classification was not clear cut and they were identified as derived from more than one chromosome. The SKY classification of the markers in Patient 1 was 1, 3, 5, 7, 11, 15, and 22 and in Patient 2 was 1, 5, 6, or 7. Patient 2 was lost to further follow-up studies. To confirm the recurring SKY classifications in Patient 1, centromere probes for chromosomes 1, 3, 5, 7, 11, 15, and 22 were used. The markers were negative for 1, 3, and 11 but positive for 7, 15, and 22 and probably 5. Since 5 centromere probe cross hybridizes with 1 and 19, the weak signal on the marker/s in successive hybridization did not give a definitive answer. Also, the 5 paint probe was not conclusive because of the minute size of the marker. In some metaphases, two markers were derived from 5 or 22. For clinical considerations, the marker derived from 7, although variable in size, appeared to consistently have euchromatin, followed by 15, while 22 and 5 markers were mostly centromeric heterochromatin. The elastin gene probe that maps to 7q11.23, SNRPN gene that maps to 15q11.2, and TUPLE gene that maps to 22q11.2 did not give a signal on the markers. As expected for a majority of ring chromosomes, the pan telomere probe did not hybridize to any of the markers. This highly unusual karyotype was confirmed in the buccal epithelium using a mix of centromere 7 and 15 probes and the combination 14/22 probe. The ratio of additional FISH signals in the buccal mucosal cells was comparable to the ratios observed in the peripheral blood. In this study, we have attempted to consolidate the data on >/=2 marker cases to understand the analysis constraints, the range of clinical abnormalities, and the mechanisms involved. The literature was surveyed for multiple markers cases. A majority of the reported cases had two markers, either derived from the same chromosome or from two different chromosomes or two cell lines with different markers derived from the same chromosome. Cases with three or more markers were rare. The nature and extent of euchromatin content of the multiple markers appears to determine the phenotype. Frequently, multiple marker cases had small to minute markers. The clinical presentation varied from mild to severe. While two bisatellited markers may be associated with infertility, the phenotype in other cases ranged from borderline intelligence and mild dysmorphism to developmental delay, mental retardation, and congenital abnormalities.
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PMID:SKY assessment of two karyotypes with 0-6 supernumerary marker/ring chromosomes and review of previously reported cases with two or more markers. 1265 96

The Williams-Beuren syndrome is a genomic disorder (prevalence: 1/7,500 to 1/20,000), caused by a hemizygous contiguous gene deletion on chromosome 7q11.23. Typical symptoms comprise supravalvular aortic stenosis, mental retardation, overfriendliness and visuospatial impairment. The common deletion sizes range of 1.5-1.8 mega base pairs (Mb), encompassing app. 28 genes. For a few genes, a genotype-phenotype correlation has been established. The best-explored gene within this region is the elastin gene; its haploinsufficiency causes arterial stenosis. The region of the Williams-Beuren syndrome consists of a single copy gene region (approximately 1.2 Mb) flanked by repetitive sequences--Low Copy Repeats (LCR). The deletions arise as a consequence of misalignment of these repetitive sequences during meiosis and a following unequal crossing over due to high similarity of LCRs. This review presents an overview of the Williams-Beuren syndrome region considering the genomic assembly, chromosomal rearrangements and their mechanisms (i.e. deletions, duplications, inversions) and evolutionary and historical aspects.
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PMID:The genomic basis of the Williams-Beuren syndrome. 1903 20

Williams-Beuren syndrome is a multysistem genetic disorder caused by the 1.6Mb hemizygous deletion involving the elastin gene in the region q11.23 of chromosome 7. The phenotype of Williams-Beuren syndrome is extremelly variable but the most common findings include cardiovascular disease, distinctive facies, mental retardation, a specific congitive profile, endocrine abnormalities, growth retardation and connective tissue abnormalities. Although gastrointestinal difficulties are one of the most constant and prominent finding of the syndrome, including gastro-esophageal reflux (GER), poor suckling, vomiting, constipation, prolonged colic, rectal prolapse, inguinal, umbilical and hiatal hernia, there have been no reports of achalasia in association with Williams-Beuren syndrome in the literature. We present the case of a boy with Williams-Beuren syndrome, achalasia and recurrent postoperative stenosis of the cardia. After Heller myotomy, the boy developed severe restenosis of the cardia with abundant adhesions which repeated after every treatment, five times in periods shorter than one month. Eventually, he developed GER, errosive gastritis and hiatal hernia which led to severe malnutrition and failure to thrive. Although the genetic defect causing Williams-Beuren syndrome might not be the direct cause of achalasia we suggest that the frequent development of severe restenosis of cardia due to tight adhesions could be the consequence of elastin gene haploinsufficiency and altered structure and function of elastic fibers in esophageal connective tissue. This case highlights the importance of early diagnosis of esophageal motor disorders in childhood which should be included in the differential diagnosis when a child with Williams-Beuren syndrome presents with dysphagia and/or regurgitation.
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PMID:Recurrent achalasia in a child with Williams-Beuren syndrome. 2205 84

Williams-Beuren syndrome (WBS) is a rare multisystem disorder caused by a hemizygous deletion of the elastin gene on chromosome 7q11.23. WBS patients have characteristic skeletal features and dental anomalies accompanied by mental retardation, a friendly outgoing personality, and mild to moderate intellectual disability or learning problems. In this case report, we present the combined orthodontic and surgical treatment of a WBS patient with an isolated cleft palate through a long-term follow-up from the age of 5 to 24 years. During the period of active treatment, comprehensive orthodontic treatment combined with maxillary anterior segmental distraction osteogenesis and prosthetic treatment using dental implants were effective in dramatically improving the patient's malocclusion. The patient's mental abilities and the cooperation shown by the patient and her family were crucial for the success of this complex and long-term treatment course.
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PMID:Orthodontic Treatment and Maxillary Anterior Segmental Distraction Osteogenesis of a Subject with Williams-Beuren Syndrome and Isolated Cleft Palate: A Long-Term Follow-Up from the Age of 5 to 24 Years. 2874 80


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