Mental retardation syndrome

Biacsi, R., Kumari, D. and Usdin, K. (2008) SIRTl inhibition alleviates gene silencing in Fragile X mental retardation syndrome. PLoS Genetics, 4, el000017. 

Rubinstein, J.H. and Taybi, H. (1963) Broad thumbs and toes and facial abnormalities. A possible mental retardation syndrome. American Journal of Diseases of Children, 105, 588-608. 

ATRX Alpha Thalassemia/mental retardation syndrome X-linked RAD54 (S. cerevisiae) homolog... 

The channelopathy present in the shiverer mutant may be relevant to understanding epileptogenesis in an inherited human chnical syndrome, 18t]. This mental retardation syndrome is of particular interest since the deleted chromosomal region contains the human orthologue of the myehn basic protein gene, and is accompanied by hypomyehnation and characteristic seizures. 

Krawitz PM, Schweiger MR, Rodelsperger C et al (2010) Identity-by-descent filtering of exome sequence data identifies PIGV mutations in hyperphosphatasia mental retardation syndrome. Nat Genet 42 827-829... 

Valverde R, Pozdnyakova I, Kajander T, Venkatraman J, Regan L. Fragile X mental retardation syndrome stmcture of the KH1-KH2 domains of fragile X mental retardation protein structure. 2007 15 1090-1098. 

These latter two studies suggest that fetal lead exposure during the critical period of brain development may cause perturbations in brain organization that are expressed later in mental retardation syndromes, and they raise for careful scrutiny the issue of postnatal risks associated with intrauterine exposure to lead. Long-term prospective studies of the type described later are beginning to produce results which address that issue. 

Figure 48-10. Simplified scheme of causation ofa mucopolysaccharidosis, such as Hurler syndrome (MIM 252800), in which the affected enzyme is a-L-iduroni-dase. Marked accumulation of the GAGs in the tissues mentioned in the figure could cause hepatomegaly, splenomegaly, disturbances of growth, coarse facies, and mental retardation, respectively.

Nineteen women underwent amniocentesis for the determination of fetal sex. Several different X-llnked abnormalities constituted the Indications for this procedure, and these Included hemophilia A, hemophilia B, Duchenne muscular dystrophy, optic albinism, X-llnked mental retardation, the Lesch-Nyhan syndrome (due to dlflclency of hypoxanthlne-guanlne phosphorlbosyltransferase, and Fabry s disease (due to deficiency of an a-galact-osldase). Fourteen of the fetuses were male. Including one which turned out to be a set of twins, and most of the male pregnancies were terminated. The sex determination being carried out for Fabry s disease Is of particular Interest, since In this case It was desired to find out whether the fetus was a female. 

Lennox-Gostaut syndrome (LGS) Patients with this syndrome have cognitive dysfunction and mental retardation. Their seizures usually consist of a combination of tonic-clonic, absence, atonic, and myoclonic seizures. 

Fetal alcohol syndrome (FAS) is a pattern of birth defects caused by maternal consumption of ethanol during pregnancy. It is recognized by growth deficiency, a characteristic set of craniofacial features and neurodevelopmental abnormalities leading to cognitive and behavioral deficits [85]. FAS is considered to be the most common non-hereditary cause of mental retardation. 

The answer is c. (Hardman, p 15.33.) Enthusiastic over medication with vitamin D may lead to a toxic syndrome called hy/jervitamijmsis D. The initial symptoms can include weakness, nausea, weight loss, anemia, and mild acidosis. As the excessive doses are continued, signs of nephrotoxicity are manifested, such as polyuria, polydipsia, azotemia, and eventually nephrocalcinosis. In adults, osteoporosis can occur. Also, there is CNS impairment, which can result in mental retardation and convulsions. 

Homocystinuria Usually a failure of cystathionine synthase (Fig. 40-2 reaction 6). Rarely associated with aberrant vitamin B12 metabolism (Fig. 40-2) Thromboembolic diathesis, marfanoid habitus, ectopia lentis. Mental retardation is frequent. Diet low in methionine Vitamin B6 in pyridoxine-responsive syndromes Vitamin B12 in responsive syndromes Anticlotting agents... 

Urea cycle defects Failure to convert ammonia to urea via urea cycle (Fig. 40-5). Coma, convulsions, vomiting, respiratoryfailure in neonate. Often mistaken for sepsis of the newborn. Mental retardation, failure to thrive, lethargy, ataxia and coma in the older child. Associated with hyperammonemia and abnormalities of blood aminogram Low protein diet Acylation therapy (sodium benzoate, sodium phenylacetate) Arginine therapy in selected syndromes Hepatic transplantation... 

Definitions of mental illness tend to contain two aspects a normative element and a functional element. Normative definitions delimit abnormal behavior in light of what is typical, usual, or the norm. Some degree of deviance from the norm is necessary for a behavior to be considered abnormal. Deviance alone, however, is never sufficient for a label of abnormality. High IQ is just as deviant as low IQ, but only mental retardation is labeled abnormal. This leads us to the functional element of the definition. Typically, the label of abnormality requires deviance plus maladaptation. Maladaptation suggests some diminished capacity to function relative to an average. For example, the DSM defines mental disorder as a syndrome that is associated with distress or impairment in functioning (American Psychiatric Association, 1994, pp- xxi-xxii). 

The phenomenon of imprinting refers to the fact that a small number of human genes are transcriptionally active only when transmitted by one of the two sexes. A good example is provided by Prader-Willi syndrome, a disorder characterized by moderate mental retardation, hypogonadism, small hands and feet, and obesity. Most cases of Prader-Willi syndrome are caused by a deletion of 4 million bases (4 megabases or Mb) on the long arm of chromosome 15. However, the deletion produces this syndrome only if it is transmitted by the fether. If the same deletion is... 

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