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)

Cephalic neural crest cells contribute to the formation of the external and middle ears, the supporting cells of the statoacoustic ganglion, other cranial nerve components, and the face. The anlage of otic sensory structures receive inductive stimuli from adjacent rhombencephalic tissue. The complex series of interactions that guide organogenesis of the outer, middle, and inner ear structures may explain why neurologic dysfunction is likely to be associated with malformations of the ear. We reviewed the records of 100 patients with complex ear anomalies with or without hearing loss. Mean age was 4.2 years (range 1 day-27 years). Malformations, either bilateral (70) or unilateral (30), involved the external ear (94), middle ear (16), and/or inner ear (12). Eighty-five patients had neurologic dysfunction. Cranial nerve dysfunction was found in 56 patients and involved nerves VIII (39 auditory and/or vestibular), VII (22), II (11), VI (8), V (4), III (3), X (3), XII (1), and IX (1). Sixty-four patients had evidence of central nervous system dysfunction such as mental deficiency/developmental delay (44), non-paretic gait disorders (17), hypotonia (16), microcephaly (13), seizures (8), motor deficits (8), autistic features (7), and radiographically confirmed intracranial abnormalities (5). Eleven of 19 children with hypoactive vestibules had delayed motor development or poor balance. Seventy-four patients had anomalies in other organ systems: 56 craniofacial, 28 osseous, 19 cardiac, 16 genito-urinary, 14 ocular, 11 gastrointestinal, and 7 cutaneous. Sixty-one patients had syndromic conditions, 32 of them branchial arch syndromes. The level of cognitive competence was not related to severity of craniofacial, ear, or cranial nerve abnormality. Children with ear malformations deserve neurologic and pediatric evaluations in addition to an otologic work-up.
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PMID:Neurologic findings in children with ear malformations. 362 8

Dyrk-related kinases represent a novel subfamily of protein kinases with unique structural and enzymatic features. Its members have been identified in distantly related organisms. The yeast kinase, Yak1, has been characterized as a negative regulator of growth. Mnb from Drosophila is encoded by the minibrain gene, whose mutation results in specific defects in neurogenesis. Its mammalian homolog, Dyrk1A, is activated by tyrosine phosphorylation in the activation loop between subdomains VII and VIII of the catalytic domain. The human gene for Dyrk1A is located in the "Down syndrome critical region" of chromosome 21 and is therefore a candidate gene for mental retardation in Down syndrome. More recently, six additional mammalian Dyrk-related kinases have been identified (Dyrk1B, Dyrk1C, Dyrk2, Dyrk3, Dyrk4A, and Dyrk4B). All members of the Dyrk family contain in the activation loop the tyrosines that are essential for the full activity of Dyrk1A. Outside their catalytic domains, Dyrk kinases exhibit little sequence similarity except for a small segment immediately preceding the catalytic domain (DH-box, Dyrk homology box). An unusual enzymatic property of Dyrk-related kinases is their ability to catalyze tyrosine-directed autophosphorylation as well as phosphorylation of serine/threonine residues in exogenous substrates. The exact cellular function of the Dyrk kinases is yet unknown. However, it appears reasonable to assume that they are involved in the regulation of cellular growth and/or development.
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PMID:Structural and functional characteristics of Dyrk, a novel subfamily of protein kinases with dual specificity. 993 50

Congenital ataxia and mental retardation are mainly caused by variations in the genes that affect brain development. Recent reports have shown that mutations in the CA8 gene are associated with mental retardation and ataxia in humans and ataxia in mice. The gene product, carbonic anhydrase-related protein VIII (CARP VIII), is predominantly present in cerebellar Purkinje cells, where it interacts with the inositol 1,4,5-trisphosphate receptor type 1, a calcium channel. In this study, we investigated the effects of the loss of function of CARP VIII during embryonic development in zebrafish using antisense morpholino oligonucleotides against the CA8 gene. Knockdown of CA8 in zebrafish larvae resulted in a curved body axis, pericardial edema and abnormal movement patterns. Histologic examination revealed gross morphologic defects in the cerebellar region and in the muscle. Electron microscopy studies showed increased neuronal cell death in developing larvae injected with CA8 antisense morpholinos. These data suggest a pivotal role for CARP VIII during embryonic development. Furthermore, suppression of CA8 expression leads to defects in motor and coordination functions, mimicking the ataxic human phenotype. This work reveals an evolutionarily conserved function of CARP VIII in brain development and introduces a novel zebrafish model in which to investigate the mechanisms of CARP VIII-related ataxia and mental retardation in humans.
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PMID:Abnormal cerebellar development and ataxia in CARP VIII morphant zebrafish. 2308 22