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)

In a study of 35 index patients who developed myotonic dystrophy between birth and 30 years (neonatal cases aware excluded), 30 could be categorised into two clinical types. The 13 type 1 patients had a more severe limb weakness, of patchy distribution, associated with proportional facial weakness. The 17 type 2 patients had a milder and more diffuse limb weakness; their facial weakness, however, was very pronounced and preceded the limb weakness by several years. All but one of the 25 affected relatives who were examined belonged to the same category as their index relative, providing evidence that the cause of the clinical heterogeneity was genetic. Subsequent observations showed that mental retardation, male infertility, and neonatally affected offspring were commoner in type 2 patients. Congenital myotonic dystrophy could occur among the offspring of either affected males or affected females, but neonatal symptoms were confined to the offspring of affected women. The overall risk for having neonatally affected offspring for this prospective study of young adult patients was 7 in 38, and for the offspring of affected females 7 in 27. The risk for having a surviving child whose mental or physical handicap or both required special schooling was 1 in 12 for males and 4 in 27 for females.
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PMID:Clinical evidence for heterogeneity in myotonic dystrophy. 714 87

Congenital myotonic dystrophy type 1 (CDM1) affects patients from birth and is associated with mental retardation and impaired muscle development. CDM1 patients carry 1000-3000 CTG repeats in the DMPK gene and display defective skeletal muscles differentiation, resulting in reduced size of myotubes and decreased number of satellite cells. In this study, human myoblasts in culture deriving from control and DM1 embryos (3200 CTG repeats) were analyzed using both a biochemical and electron microscopic approach, in order to provide new insights into the molecular mechanisms underlying such alteration. Interestingly, electron microscopy analysis showed not only ultrastructural features of abnormal differentiation but also revealed the presence of autophagic vacuoles in DM1 myoblasts not undergoing differentiation. In accordance with the electron microscopic findings, the autophagic markers LC3 and ATG5, but not apoptotic markers, were significantly up regulated in DM1 myoblasts after differentiating medium addition. The induction of autophagic processes in DM1 myoblasts was concomitant to p53 over-expression and inhibition of the mTOR-S6K1 pathway, causatively involved in autophagy. Moreover biochemical alterations of the two main signal transduction pathways involved in differentiation were observed in DM1 myoblasts, in particular decreased activation of p38MAPK and persistent activation of the MEK-ERK pathway. This work, while demonstrating that major signaling pathways regulating myoblasts differentiation are profoundly deranged in DM1 myoblasts, for the first time provides evidence of autophagy induction, possibly mediated by p53 activation in response to metabolic stress which might contribute to the dystrophic alterations observed in the muscles of congenital DM1 patients.
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PMID:Altered signal transduction pathways and induction of autophagy in human myotonic dystrophy type 1 myoblasts. 2079 47

Myotonic dystrophy type 1 (DM1) is an autosomal dominant disorder with variable expression. DM1 results from a trinucleotide expansion in the 3' untranslated region or the gene for myotonic dystrophy protein kinase (DMPK). Severity tends to increase and it shows a younger onset age with vertical transmission, a phenomenon known as anticipation. Congenital myotonic dystrophy (CDM) is classified as the most severe form of DM1, and its phenotype, with severe hypotonia, neonatal respiratory distress and feeding difficulties, is completely different from that of adult-onset type. Involvement of respiratory muscles may be the major cause of mortality in affected infants. Facial weakness with a tented upper lip is often recognized. If infants survive the neonatal period, muscle involvement symptoms gradually improve and most children do not require respiratory support or tube feeding. As CDM patients grow older, mental retardation or a developmental disorder becomes prominent. Furthermore, the main problems in childhood-onset DM, with an onset age under 10 years, are developmental disorders or learning disabilities, rather than muscle symptoms. Early meticulous support and cooperation with teachers are necessary. Medications such as methylphenidate may be helpful in DM1 children with attention deficit/hyperactivity disorder.
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PMID:[Clinical features and care of patients with congenital and childhood-onset myotonic dystrophy]. 2319 84