Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mucopolysaccharidosis type VII (MPS VII, Sly syndrome) is caused by dysfunction of the acid hydrolase beta-D-glucuronidase. The defect results in the accumulation of incompletely degraded glycosaminoglycans within lysosomes of a wide array of cell types. MPS VII is associated with mixed (conductive and sensorineural) hearing loss, vision defects, shortened stature, mental retardation and decreased lifespan. Whether the sensorineural component of hearing loss in MPS VII involves degeneration of cochlear sensory cells is not yet clear. The MPS VII mouse resembles its human counterpart in all major aspects, and has been the focus of extensive research seeking to correct MPS VII and other lysosomal storage diseases. The value of potential treatments for this hearing loss can be determined only if cochlear pathology in this model is well characterized. We examined threshold sensitivity, frequency tuning, hair cell density and the appearance of the cochlea and vestibular organs in MPS VII mice ranging from 1.0 to 7.5 months of age. At all ages, lysosomal storage is pronounced within cells of spiral limbus, spiral prominence, spiral ligament and glial cells, but not within organ of Corti, stria vascularis, or neurons. Within the vestibular maculae and cristae, both hair cells and supporting cells also show lysosomal storage. Although hearing thresholds are never normal, reduction in the sharpness of frequency tuning is not apparent until 2.5 months of age, suggesting that the sensorineural component of hearing loss begins in adulthood. No evidence was found for cell loss within the organ of Corti, or any other structure, however. Our results suggest that sensorineural hearing loss in the MPS VII mouse is not caused by degeneration, but may arise from alterations in mass and stiffness of cochlear structures or impaired sensory cell function. They also indicate a possible vestibular component in MPS VII.
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PMID:Inner ear pathology in the mucopolysaccharidosis VII mouse. 1212 41

We report a familial case with a proximal interstitial deletion of chromosome 21q [del(21q)]. Although the mother in the family was phenotypically normal, her first child was affected with both sensorineural hearing loss and moderate mental retardation, and the second affected child had mild mental retardation but not sensorineural hearing loss. We determined breakpoints of the del(21q) in the mother and her two affected children by fluorescence in situ hybridization analysis using 45 DNA clones and the molecular analysis using 21 DNA markers. The proximal breakpoint of the del(21q) was located at a region between 0.33 Mb and 0.46 Mb distal to the centromere, and the distal breakpoint was at a region between 14.6 Mb and 14.9 Mb. The finding indicates that the three individuals had an approximate 14-Mb deletion within 21q11.2-q21.3. Molecular analysis showed that both affected children shared the same maternal haplotype of their del(21q), but a crossover was detected in the paternally inherited normal chromosome 21. These data suggest that unmasking of deleterious genes on the paternally derived chromosome 21 of the two children as a result of the deletion may affect the extent of their mental retardation and/or sensorineural hearing loss. Usher syndrome 1E may be a candidate disease locus related to the sensorineural hearing loss of the first child.
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PMID:Familial 14-Mb deletion at 21q11.2-q21.3 and variable phenotypic expression. 1237 39

Congenital cytomegalovirus (CMV) infection is a major cause of sensorineural hearing loss and mental retardation, whose annual healthcare costs in the USA approximate to one billion dollars. Only a minority of neonates with this infection has symptoms present at birth and some of the damage to ear and brain occurs in the first few months of life. Extensive studies of CMV infection have been conducted in pregnant women and their children to define the natural history of this infection. What is required now is a concerted commitment to tackle this clinical problem using one or more of the following strategies: avoid iatrogenic transmission; advise those at risk how to avoid acquisition; provide diagnosis in an individual neonate or pregnant woman and offer treatment; develop and deploy a CMV vaccine.
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PMID:Strategies to prevent CMV infection in the neonate. 1240 Dec 99

The Johanson-Blizzard Syndrome (JBS) is an autosomal recessive disorder with a characteristic phenotype, including dwarfism, a beaked nose with aplastic alae nasi, a high forehead, mid-line ectodermal scalp defects with sparse hair and absent eyelashes/eyebrows, prominent scalp veins, low set ears, a large anterior fontanelle, micrognathia, thin lips, absent permanent dentition and microcephaly. In addition to the characteristic facial features, associated conditions include congenital heart disease, exocrine/endocrine pancreatic dysfunction, hypothyroidism, hypopituitarism, mental retardation, sensorineural hearing loss and vesico-ureteral reflux. A case is presented and the potential anaesthetic implications of this syndrome are discussed.
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PMID:Perioperative care of the child with the Johanson-Blizzard syndrome. 1253 44

We describe two brothers with a unique pattern of malformations that includes coloboma (iris, optic nerve), high forehead, severe retrognathia, mental retardation, and agenesis of the corpus callosum (ACC). Both boys have low-set cupped ears with sensorineural hearing loss, normal phallus, pectus excavatum, scoliosis, and short stature. One brother had choanal atresia and cardiac defects consisting of ventricular septal defect (VSD) and patent ductus arteriosus (PDA) which resolved spontaneously. Differential diagnosis between a number of clinical entities was considered, however, because ACC and the distinctive facial features were reminiscent of FG syndrome, DNA was analyzed for markers linked to the FGS1 locus at Xq13-q21. Notably, the brothers were concordant for markers spanning this presumed FG region, and in both we have identified adjacent alterations (-57delT and T-55A) in the Alpha 4 gene located within this interval. Alpha 4 is a regulatory subunit of the major cellular phosphatase, PP2A, that has recently been shown to interact with MID1, the product of the gene mutated in X-linked Opitz GBBB syndrome. The double nucleotide change identified in this family was not observed in 410 control chromosomes, suggesting that it may be a pathogenetic change. Altered expression of Alpha 4, through either a change in translational efficiency, mRNA stability or splicing, could explain the clinical phenotype in these boys and the phenotypic overlap with Opitz GBBB syndrome.
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PMID:A new X-linked syndrome with agenesis of the corpus callosum, mental retardation, coloboma, micrognathia, and a mutation in the Alpha 4 gene at Xq13. 1455 45

Carpenter syndrome (Acrocephalopolysyndactyly type II), first described in 1901, consists of acrocephaly, syndactyly, polydactyly, congenital heart disease, mental retardation, hypogenitalism, cryptorchidism, obesity, umbilical hernia and bony abnormalities. We report a 6 years old boy presenting as a union of these malformations and also having bilateral sensorineural hearing loss. Auditory disturbances are not common among Carpenter syndrome patients. According to our knowledge, this is the first Carpenter syndrome case whose hearing loss is demonstrated by auditory brainstem response (ABR) test.
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PMID:The carpenter syndrome phenotype. 1512 47

Cerebellar ataxia has been described as being associated with hypogonadism for almost 100 years. In the majority of cases, hypogonadism is hypogonadotropic. The association of cerebellar ataxia with hypergonadotropic hypogonadism is a rare genetic disorder with a recessive mode of inheritance. Cerebellar ataxia and hypogonadism can also occur associated with a large spectrum of additional clinical manfestations, including mental retardation, sensorineural deafness, choroidal dystrophy, ectodermal dysplasia and short stature, and polyneuropathy. We report the case of a woman with early-onset spinocerebellar ataxia, primary amenorrhea due to hypergonadotropic hypogonadism, and late-onset sensorineural hearing loss. Additional family members from the father's side are affected with late-onset hearing loss, suggesting a dominant mode of inheritance.
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PMID:Spinocerebellar ataxia and hypergonadotropic hypogonadism associated with familial sensorineural hearing loss. 1562 72

Fragile X syndrome (FXS) is the most common inherited cause of mental retardation resulting in developmental delays in males. Atypical outer ear morphology is characteristic of FXS and may serve as a marker for abnormal auditory function. Despite this abnormality, studies of the hearing of young males with FXS are generally lacking. A few studies have suggested that a significant proportion of individuals with FXS demonstrate prolonged auditory brainstem response (ABR) latencies. The purpose of this study was to determine whether young males with FXS display atypical auditory brainstem function compared to typically developing males when conductive and sensorineural hearing loss are ruled out as possible contributors to atypical findings. Participants were 23 males with FXS, 21 typically developing males who were matched for developmental age, and 17 typically developing males who were matched for chronological age. A battery of tests to assess peripheral hearing, cochlear function, and auditory pathway integrity through the level of the brainstem was completed. Males with FXS were similar to typically developing males who were matched for developmental age level or chronological age level on all measures. They had normal hearing sensitivity and middle ear function and scored similar to the typically developing children on the measures of auditory brainstem pathway integrity. In summary, ABRs in young males with FXS were within normal limits.
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PMID:Auditory brainstem responses in young males with Fragile X syndrome. 1598 7

Cytomegalovirus (CMV) is the most common cause of congenital infection in humans. Some congenitally infected infants will develop sequelae later in life, especially sensorineural hearing loss (SNHL) and mental retardation. There is no generally accepted antiviral therapy for the treatment of symptomatic congenital CMV infections yet. We present a neonate with symptomatic congenital CMV infection, who was treated with intravenous (iv) ganciclovir (GCV) during 18 days and subsequently with oral valganciclovir (VGCV) for 5.5 months, in an attempt to prevent development of SNHL. GCV was given intravenously 10 mg/kg/day in two doses and VGCV doses ranged from 280-850 mg/m2 bidaily (bid). Our experience shows that it is not possible to give a fixed dosing regime for VGCV in neonates and that continuous adaptation of dose is necessary to achieve stable target levels of GCV and to keep the viral load in urine at undetectable level. At 18 months of age no hearing deterioration has occurred. While the current findings are encouraging, the limitations of a single case report with a relatively short follow-up emphasizes the need for further prospective randomized studies to evaluate pharmacokinetics, efficacy and safety of VGCV therapy in neonates with congenital CMV infection.
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PMID:Treatment of symptomatic congenital cytomegalovirus infection with valganciclovir. 1621 80

Congenital and perinatal infections with cytomegalovirus (CMV) are responsible for considerable short- and long- term morbidity in infants. CMV is the most common congenital viral infection in the developed world, and is a common cause of neurodevelopmental injury, including mental retardation and sensorineural hearing loss (SNHL). Antiviral therapy has been shown to be valuable in ameliorating the severity of SNHL, but CMV disease control in newborns ultimately depends on successful development of a vaccine. Because CMVs are extremely species specific, preclinical evaluation of vaccines must be performed in animal models using the appropriate CMV of the animal being studied. Several small animal models available for CMV vaccine and pathogenesis research are described. The discussion focuses on the guinea pig model because guinea pig cytomegalovirus (GPCMV), which crosses the placenta and causes infection in utero, is uniquely useful. Examination of vaccines in the GPCMV and other nonprimate models should provide insights into the determinants of the host response that protect the fetus, and may help to prioritize potential vaccine strategies for use in human clinical trials related to this important public health problem.
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PMID:Nonprimate models of congenital cytomegalovirus (CMV) infection: gaining insight into pathogenesis and prevention of disease in newborns. 1639 32


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