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R Stevenson

Publications and source records attributed to R Stevenson.

98 records · Page 6Linked to original sources
PubMedDate not supplied

Nomenclature guidelines for X-linked mental retardation.

Nomenclature guidelines are proposed for non-specific and for syndromal forms of X-linked mental retardation. Non-specific mental retardations (MRX) are given unique symbols for each family (MRX1, MRX2, MRX3 ...). Syndromal mental retardations (MRXS) which do not as yet have specific symbols are given unique interim symbols for each syndrome (MRXS1, MRXS2, MRXS3 ...). The prerequisite for assignment of serial MRX and MRXS gene symbols is a minimum lod score (or multipoint lod score) of +2 between the MR locus and one or more X chromosome markers. Prior approval of availability for proposed gene symbols must be obtained from the Nomenclature Committee of the Human Gene Mapping Workshops.

Chromosome Mapping↗
PubMedDate not supplied

Spastic paraplegia with iron deposits in the basal ganglia: a new X-linked mental retardation syndrome.

We report on a family with X-linked mental retardation (XLMR) and severe spastic paraplegia. Appearance is normal but there is severe involvement of the lower limbs (affected relatives never walked), with minimal involvement of the upper limbs and unusual MRI findings including macrogyria, white matter hypoplasia, lack of myelination and a markedly increased paramagnetic signal suggestive of iron deposition. Linkage studies documented possible linkage, with no recombination, between the disease locus and DXS424. A 7-point linkage analysis yielded a maximum LOD score of 1.9, (theta = 0.00) for three loci spanning Xq22-q25. The combination of the unusual clinical and MRI findings and the tentative localization to a region different than other XLMR syndromes with spastic paraplegia, provide good evidence that this is a new XLMR syndrome.

Adult↗
PubMedDate not supplied

Synthesis of lignan aryldihydronaphthalene lactones by cyclization of cinnamyl arylpropiolate esters: revised structure of beta-apopolygamatin.

Unlike arylpropargyl arylpropiolates (e.g., 3) which yield, on heating in xylene, arylnaphthalene type I and type II lactones (4 and 5, respectively) in 1:1 ratio, cinnamyl arylpropiolates (e.g., 7) on heating in DMF gave the aryldihydronaphthalene-2-carboxylic acid lactones (e.g., 8) in excellent yield and regioselectivity. It is suggested that the aryldihydronaphthalene lactone product isolated from the tumor-inhibiting extract of Polygala polygama and previously named beta-apopolygamatin [17] has in fact the structure 1-(3',4'-methylene-dioxyphenyl)-3-hydroxymethyl-7,8-dimethoxy-3,4- dihydro-2- naphthoic acid lactone [18].

Cinnamates↗
PubMedDate not supplied

Deletion of Huntington's disease-linked G8 (D4S10) locus in Wolf-Hirschhorn syndrome.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by progressive involuntary movements and dementia. The symptoms of the disease, although devastating in severity, do not usually appear until the third to fourth decade of life. The gene defect is highly penetrant, and results in the loss of neurones in the basal ganglia, globus pallidus, and more diffusely in the cortex. A DNA marker, G8 (or D4S10), is tightly linked to Huntington's disease and this gene has been localized to chromosome 4 (ref. 3). The discovery of this linkage marker raises the possibility of developing a presymptomatic test for the disorder, and of eventually isolating the disease gene based on its map position. We have now regionally localized the DNA marker G8 to the terminal band of the short arm of the chromosome, a region representing approximately 0.5% of the total human genome. The assignment was made by examining DNA from patients with Wolf-Hirschhorn syndrome, a birth defect resulting from partial heterozygous deletion of the short arm of chromosome 4.

Abnormalities, Multiple↗