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Query: UMLS:C0025362 (mental retardation)
 15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In 1977 Harrod et al. [BD:OAS XIII (3B): 111-115] reported 2 brothers with an unusual syndrome of mental retardation, unusual facial appearance, large protruding ears, arachnodactyly, hypogenitalism, failure to thrive, and minor anomalies. We report on a 46-year-old man with striking resemblance to the children described by Harrod who also has secondary megacolon and varicose veins, suggesting a connective tissue disorder.
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PMID:Additional case of craniofacial and digital anomalies as reported by Harrod et al. 866 46

We report on an aneuploidy syndrome due to the unbalanced segregation of a familial translocation (4;21)(p16.3;q22.1) causing a partial 4p monosomy and a partial 21q trisomy. The three affected children presented with severe failure to thrive, short stature, microcephaly, profound hypotonia, and mental retardation. The face, very similar in the three children, is characterized by frontal bossing, upslanting of the palpebral fissures, short nose, and deep set ears, giving the overall appearance of the Down syndrome. The molecular study has defined the aneuploid segment on both 4p and 21q. Most of the Down syndrome critical region was found to the trisomic, while only part of the candidate Wolf-Hirschhorn syndrome critical region was deleted, suggesting that this region is not critical for the major malformations characteristic for WHS.
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PMID:Molecular and cytogenetic characterization of a recurrent unbalanced translocation (4;21)(p16.3;q22.1): relevance to the Wolf-Hirschhorn and Down syndrome critical regions. 872 87

Gorlin syndrome is an autosomal dominant disorder characterized by multiple basal cell carcinomas, medulloblastomas, ovarian fibromas, and a variety of developmental defects. All affected individuals share certain key features, but there is significant phenotypic variability within and among kindreds with respect to malformations. The gene (NBCCS) maps to chromosome 9q22, and allelic loss at this location is common in tumors from Gorlin syndrome patients. Two recessive cancer-predisposition syndromes, xeroderma pigmentosum group A (XPAC) and Fanconi anemia group C (FACC), map to the NBCCS region; and unusual, dominant mutations in these genes have been proposed as the cause of Gorlin syndrome. This study presents cytogenetic and molecular characterization of germ-line deletions in one patient with a chromosome 9q22 deletion and in a second patient with a deletion of 9q22-q3l. Both have typical features of Gorlin syndrome plus additional findings, including mental retardation, conductive hearing loss, and failure to thrive. That Gorlin syndrome can be caused by null mutations (deletions) rather than by activating mutations has several implications. First, in conjunction with previous analyses of allelic loss in tumors, this study provides evidence that associated neoplasms arise with homozygous inactivation of the gene. In addition, dominant mutations of the XPAC and FACC1 genes can be ruled out as the cause of Gorlin syndrome, since the two patients described have null mutations. Finally, phenotypic features that show variable expression must be influenced by genetic background, epigenetic effects, somatic mutations, or environmental factors, since these two patients with identical alterations (deletions) of the Gorlin syndrome gene have somewhat different manifestations of Gorlin syndrome.
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PMID:Molecular analysis of chromosome 9q deletions in two Gorlin syndrome patients. 875 29

All of vitamin B12 in nature is of microbial origin. Cobalamin, as vitamin B12 should correctly be termed, is a large polar molecule that must be bound to specialized transport proteins to gain entry into cells. Entry from the lumen of the intestine under physiological conditions occurs only in the ileum and only when bound to intrinsic factor. It is transported into all other cells only when bound to another transport protein, transcobalamin II. Congenital absence or defective synthesis of intrinsic factor or transcobalamin II result in megaloblastic anemia. The Immerslund-Graesbeck syndrome, a congenital defect in the transcellular transport of cobalamin through the ileal cell during absorption, also presents with megaloblastic anemia, but with accompanying albuminuria. In most bacteria and in all mammals, cobalamin regulates DNA synthesis indirectly through its effect on a step in folate metabolism, the conversion of N5-methyltetrahydrofolate to tetrahydrofolate, which in turn is linked to the conversion of homocysteine to methionine. This reaction occurs in the cytoplasm, and it is catalyzed by methionine synthase, which requires methyl cobalamin (MeCbl), one of the two coenzyme forms of the vitamin, as a cofactor. Defects in the generation of MeCbl (cobalamin E and G diseases) result in homocystinuria; affected infants present with megaloblastic anemia, retardation, and neurological and ocular defects. 5'-Deoxyadenosyl cobalamin (AdoCbl), the other coenzyme form of cobalamin, is present within mitochondria, and it is an essential cofactor for the enzyme Methylmalonyl-CoA mutase, which converts L-methylmalonyl CoA to succinyl CoA. This reaction is in the pathway for the metabolism of odd chain fatty acids via propionic acid, as well as that of the amino acids isoleucine, methionine, threonine, and valine. Impaired synthesis of AdoCbl (cobalamin A or B disease) results in infants with methylmalonic aciduria who are mentally retarded, hypotonic, and who present with metabolic acidosis, hypoglycemia, ketonemia, hyperglycinemia, and hyperammonemia. Megaloblastic anemia does not develop in these children because adequate amounts of MeCbl are present, but the effect of methylmalonic acid on marrow stem cells may give rise to pancytopenia. Congenital absence of reductases in the cytoplasm, which normally reduce the cobalt atom in cobalamin from its oxidized to its reduced state (cobalamin C and D diseases), results in impaired synthesis of both MeCbl and AdoCbl. Both methylmalonic aciduria and homocystinuria therefore develop in these children, and they present with megaloblastosis, mental retardation, a host of neurological and ocular disorders, and failure to thrive; however, they do not have hyperglycinemia or hyperammonemia. A similar biochemical profile and clinical presentation is also seen in cobalamin F disease, which results from a defect in the release of cobalamin from lysosomes, following receptor-mediated endocytosis of the transcobalamin II-cobalamin complex into cells. It is important to recognize these inborn errors of cobalamin absorption, transport, or function as soon after birth as possible, because most respond (in some patients more fully than others) to parenteral administration of cobalamin. Delays in diagnosis can lead to grave clinical consequences.
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PMID:Vitamin B12 in health and disease: part I--inherited disorders of function, absorption, and transport. 877 94

Smith-Lemli-Opitz syndrome (SLOS) is a common autosomal recessive disorder. Children with SLOS present with specific facial dysmorphism and have multiple congenital anomalies including cleft palate, congenital heart disease, genitourinary anomalies, and limb abnormalities. They also manifest severe failure to thrive and mental retardation. A metabolic defect at the final step in the cholesterol biosynthetic pathway has been described in SLOS patients. This defect results in markedly reduced cholesterol levels and abnormal accumulation of cholesterol precursors, particularly 7-dehydrocholesterol. This newly described metabolic defect in humans is one of only a few metabolic errors known to cause multiple birth defects. The biochemical profile of reduced plasma cholesterol levels in association with markedly elevated levels of the cholesterol precursor 7-dehydrocholesterol is now used to confirm the diagnosis of SLOS, which was formerly made on purely clinical grounds. This biochemical abnormality has been confirmed in dozens of patients with SLOS in both the United States and Europe. The severe cholesterol deficiency seen in these patients has multiple effects on health and early childhood development, because cholesterol is an essential component of many cell functions, which explains many of the clinical findings seen in SLOS.
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PMID:Abnormal cholesterol metabolism in Smith-Lemli-Opitz syndrome. 877 24

Dehydration in developed countries is an uncommon but important mechanism resulting in the death of infants and children. The clinicopathological features of a series of 37 fatal dehydration cases autopsied at the Adelaide Children's Hospital over a 33-year period (1961-1993) are presented. Causative factors for dehydration included gastroenteritis (21 cases), gastroenteritis with high environmental temperature (one case), high environmental temperatures (six cases), neglect/failure to thrive (four cases), mental retardation/chromosomal abnormality (three cases), congenital adrenal hyperplasia (one case), and unsuspected cystic fibrosis (one case). The mean age at death was 11.4 months (range 2 weeks to 6.25 years; median 6 months; 95% confidence interval 6 months to 1 year and 4 months; male-to-female ratio, 19:18). Sixteen of the 22 cases of fatal gastroenteritis (73%) occurred during the fall/winter months (March to August). There were a total of seven aboriginal or part aboriginal children in the group (19%). Children with mental retardation were at higher risk of dehydration, and previously unsuspected cases of child abuse/neglect also presented with lethal dehydration. Vitreous humor electrolyte levels and immunoassay for rotavirus were useful diagnostic adjuncts.
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PMID:Dehydration deaths in infants and young children. 883 76

To delineate further the clinical spectrum of Menkes disease, an X-linked recessive disorder of copper transport, we studied 4 related males, ranging in age from 4-38 years, with a unique phenotype that combines manifestations of classical and mild Menkes disease and occipital horn syndrome (OHS). The propositus, and 18-year-old man, was evaluated following an intracerebral hemorrhage at age 15 years and was noted to have marked hypotonia, motor delay with mental retardation, bladder diverticula, failure to thrive, and diarrhea from infancy; seizures from age 3 years; and abnormal hair (pili torti) and face, cutis laxa, and multiple joint dislocations. Radiographic abnormalities included occipital exostoses, tortuous cerebral blood vessels with multiple branch occlusions, and hammer-shaped clavicles. Biochemical studies demonstrated reduced copper and ceruloplasmin levels in serum, and abnormal plasma catecholamine ratios. We reported previously the molecular defect in this family, a splice-site mutation that predicts formation of approximately 20% of the normal Menkes gene product [Kaler et al., 1994: Nat Genet 18:195-202]. Here, we detail the clinical course and physical features and radiographic findings in these 4 individuals, and compare their phenotype with classical and mild Menkes and OHS. Unusual Menkes disease variants such as this may escape recognition due to anomalies that appear inconsistent with the diagnosis, particularly prolonged survival and later onset of seizures. Males with mental retardation and connective tissue abnormalities should be evaluated for biochemical evidence of defective copper transport.
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PMID:Distinctive Menkes disease variant with occipital horns: delineation of natural history and clinical phenotype. 891 40

5p- is a well-defined syndrome, but phenotypic correlations of 5q are poorly described in the literature. We present a case of a female child with interstitial deletion in the 5q13.1q15 region. Comparison of the clinical features of this patient with others reported in the literature suggests an emerging clinical syndrome defined by short stature, failure to thrive, mental retardation, slanting palpebral fissures, malformed ears, short neck and depressed nasal bridge. Based on our endocrine testing, we hypothesize that the short stature could be, in part, due to growth hormone deficiency. The recent assignment of growth hormone receptor gene to the short arm of chromosome 5 and the presence of several genes for growth factors and growth factor receptors on 5q raise interesting possibilities for the explanation of short stature in such cases.
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PMID:Interstitial deletion of long arm of chromosome no. 5 with growth hormone deficiency--an emerging syndrome? 908 35

The heterogeneous group of craniotubular dysplasias is characterized by modeling errors of the craniofacial and tubular bones. Some conditions in this category cause not only skeletal abnormalities but also a variety of mesoectodermal dysplasias, as exemplified in Lenz-Majewski syndrome (MIM 151050), which comprises craniodiaphyseal dysplasia, failure to thrive, mental retardation, proximal symphalangism, enamel hypoplasia, and loose skin. We report on a boy with a hitherto unknown multisystem disorder, including skeletal changes that were regarded as a form of craniotubular dysplasia. The patient had a large head, exophthalmos, a broad nasal root, anteverted nostrils, large auricles, thick lips, micrognathia, severe postnatal growth retardation with emaciation, severe mental retardation, sparse hair growth, enamel hypoplasia, and thin, loose skin with hyperlaxity. Skeletal changes consisted of thickened calvaria, sclerosis of the skull base and facial bones, thick ribs, and metaphyseal undermodeling of the tubular bones. In addition, generalized osteopenia was evident. The present disorder overlaps phenotypically with Lenz-Majewski syndrome; nevertheless, the absence of diaphyseal hyperostosis and proximal symphalangism in the present patient was not consistent with Lenz-Majewski syndrome.
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PMID:Craniotubular dysplasia with severe postnatal growth retardation, mental retardation, ectodermal dysplasia, and loose skin: Lenz-Majewski-like syndrome. 921 75

In a case of mosaic trisomy 22 the trisomic cells were detected primarily in fibroblasts. Results of initial lymphocyte chromosome analysis were normal. However, mosaicism was suspected because the patient had hypomelanosis of Ito, hemiatrophy, failure to thrive, and mental retardation. Mosaicism was confirmed in cultured fibroblasts. Repeat cytogenetic analysis of peripheral blood demonstrated a low level of trisomic metaphase cells, which was confirmed by interphase fluorescent in situ hybridization (FISH) analysis. Molecular studies supported maternal disomy in the child's disomic cells. The phenotype of this condition overlaps that of non-mosaic trisomy 22 chromosome mosaicism in general and to some extent the Ullrich-Turner syndrome phenotype. Improved cytogenetic and molecular techniques now allow better delineation of aneuploidy syndromes. Molecular and FISH studies added information about this case (mosaicism and uniparental disomy) not appreciated by routine cytogenetic analysis of lymphocytes. The detection of low-level mosaicism and/or uniparental disomy in such cases may change the clinical classification and our understanding of pathogenesis and recurrence risk of these disorders.
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PMID:Mosaic trisomy 22: a case presentation and literature review of trisomy 22 phenotypes. 955 7


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