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)

We recently described a novel congenital muscular dystrophy (CMD) syndrome characterized by mental retardation, microcephaly, and partial merosin deficiency on muscle biopsy. Linkage analysis excluded involvement of the known CMD loci. We now report on a study performed on the differentiation of cultured myoblasts from one patient affected by this condition to evaluate the potential to form myotubes and merosin processing in these cells. The differentiation rate was comparable to controls and myotubes were stable in culture. Biochemical analysis showed the expected 80-kDa merosin subunit in myoblasts. However, a shifted 60-kDa protein was detected in myotubes. Matrix-metalloproteinases (MMPs) zymography showed increased gelatinolytic activity, and immunoblotting identified an increased amount of membrane-type 1 matrix-metalloproteinase in pathological myotube preparations. Our results show that these CMD-derived myotubes contain a low molecular weight merosin. They further suggest that an altered regulation of MMPs can be involved in basal lamina damage.
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PMID:Unusual laminin alpha2 processing in myoblasts from a patient with a novel variant of congenital muscular dystrophy. 1106 6

We describe a 14-year-old boy with congenital bilateral cataracts, blepharophimosis, ptosis, choanal atresia, sensorineural hearing loss, short, webbed neck, poor esophageal motility, severe growth and mental retardation, skeletal anomalies, seizures, and no speech. As an infant, he had transient hypogammaglobulinemia requiring IVIG therapy. Cytogenetic studies show an apparently de novo visible duplication at 1p36.3. Fluorescence in situ hybridization (FISH) studies confirm that the common region for the 1p36 deletion syndrome (p58) is duplicated. Probes for D1Z2 at 1p36.3 and the subtelomeric region of 1p (TEL1p) are also duplicated. Array comparative genomic hybridization (aCGH) studies were done at three separate laboratories, each with somewhat different results. BAC whole genome array CGH suggests a single clone gain at the 1p terminus and a single clone deletion at 1p36.3. A targeted BAC array panel with higher resolution at the distal 1p36 region detects a telomeric duplication and an interstitial deletion. Oligonucleotide whole genomic aCGH shows the highest resolution and a more complex rearrangement: two duplications, an interstitial deletion, and a normal region. The MMP23A/B "matrix metalloproteinase 23A/B" genes are within the distal duplication region in our patient, and this patient does not have craniosynostosis. This is the first association of congenital cataracts, choanal atresia, and transient immune abnormalities with 1p36 duplication/deletion. This case illustrates the limitations of different cytogenetic technologies, and shows how three separate aCGH platforms allow for refined delineation and interpretation of the complex cytogenetic rearrangement which would not have been discovered by standard high-resolution chromosome analysis.
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PMID:Cytogenetic and array CGH characterization of de novo 1p36 duplications and deletion in a patient with congenital cataracts, hearing loss, choanal atresia, and mental retardation. 1892 66

Normal brain development depends on tight temporal and spatial regulation of connections between cells. Mutations in L1cam, a member of the immunoglobulin (Ig) superfamily that mediate cell-cell contacts through homo- and heterophilic interactions, are associated with several developmental abnormalities of the nervous system, including mental retardation, limb spasticity, hydrocephalus, and corpus callosum aplasia. L1cam has been reported to be shed from the cell surface, but the significance of this during different phases of brain development is unknown. We here show that ADAM10-mediated shedding of L1cam is regulated by its fibronectin type III (FNIII) domains. Specifically, the third FNIII domain is important for maintaining a conformation where access to a membrane proximal cleavage site is restricted. To define the role of ADAM10/17/BACE1-mediated shedding of L1cam during brain development, we used a zebrafish model system. Knockdown of the zebrafish, l1camb, caused hydrocephalus, defects in axonal outgrowth, and myelination abnormalities. Rescue experiments with proteinase-resistant and soluble L1cam variants showed that proteolytic cleavage is not required for normal axonal outgrowth and development of the ventricular system. In contrast, metalloproteinase-mediated shedding is required for efficient myelination, and only specific fragments are able to mediate this stimulatory function of the shedded L1cam.
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PMID:L1cam-mediated developmental processes of the nervous system are differentially regulated by proteolytic processing. 3084 11