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Biomedical subjects

M N Patterson

Publications and source records attributed to M N Patterson.

29 records · Page 2Linked to original sources

Linear order of new and established DNA markers around the fragile site at Xq27.3.

We have used recombinant clones derived from microdissection of the fragile X region to characterize breakpoints around the fragile site at Xq27.3. So far, no microdissection markers derived from Xq28 material have been found, thus allowing a rapid screening for clones surrounding the fragile site by their presence in a somatic cell hybrid containing Xq27.2-Xqter. A total of 43 new DNA markers from Xq27 have been sublocalized within this chromosome band. Of these new DNA markers, 5 lie in an interval defined as containing the fragile X region. The saturation of Xq27 with DNA markers by microdissection demonstrates the power of this technique and provides the resources for generating a complete physical map of the region.

Blotting, Southern↗

MASA syndrome: further clinical delineation and chromosomal localisation.

MASA syndrome (mental retardation, aphasia, shuffling gait and adducted thumbs) is an X-linked disorder first described in 1974. Since that time, two further pedigrees have been reported with similar features. The main clinical features are summarised by the acronym. Kenwrick et al. reported a separate family with X-linked recessive spastic paraplegia and mental retardation and demonstrated close linkage to DXS15 and DXS52 (DX13 and St14) at Xq28. Four affected individuals in this family were said to have absence of the extensor pollicis longus. Here we report a family where two adult brothers and their nephew have the phenotype of MASA syndrome. We demonstrate by clinical and gene mapping studies that MASA syndrome is most likely the same condition as that described by Kenwrick et al., and we review its clinical course and presentation.

Abnormalities, Multiple↗

Physical mapping of DXS134 close to the DXS52 locus.

The locus DXS134 (cpX67) has been physically linked to the cluster of polymorphic loci DXS52, DXS15, and DXS33. A comparison of physical and genetic distance indicates a high rate of recombination in this region.

Genetic Linkage↗

Genetic and physical mapping of a novel region close to the fragile X site on the human X chromosome.

We report the isolation and characterization of a novel DNA marker (1A1) in Xqter in the region of the fragile X. Genetic studies in families segregating for the fragile X syndrome suggest that 1A1 lies between the disease mutation and the distal locus, DXS52. Studies in normal and fragile X families show that 1A1 is tightly linked to DXS52 (Zmax = 17.20; theta max = 0.03) and F8 (Zmax = 7.01; theta max = 0.08). Multipoint mapping of families supports the order Xcen-DXS105-FRAXA-1A1-DXS52-(F8, DXS115)-Xqter. Pulsed-field gel electrophoresis (PFGE) studies demonstrate that 1A1 defines a new region of at least 2 Mb of DNA not physically linked to DXS52 or F8, thus extending the physical map of Xq27-qter to over 4 Mb. Complex partial digestion PFGE patterns, probably due to differing degrees of methylation, are observed with 1A1 in unrelated normal and fragile-X-positive individuals, whereas other distal markers give uniform digestion profiles. Physical data suggest that 1A1 lies in a region less CpG rich than other distal markers in Xq27-qter.

Animals↗

Physical linkage of a GABAA receptor subunit gene to the DXS374 locus in human Xq28.

We report the physical linkage of the gene encoding one of the subunits of the GABAA receptor (GABRA3) to the polymorphic locus DXS374 on the human X chromosome at Xq28. X-linked manic depression and other psychiatric disorders have been mapped to this region, and thus GABRA3 is a potential candidate gene for these disorders. DXS374--and therefore GABRA3--lies distal to the fragile X locus at a recombination fraction of approximately .15.

DNA Probes↗

Fine mapping of glycerol kinase deficiency and congenital adrenal hypoplasia within Xp21 on the short arm of the human X chromosome.

We have studied patients with Duchenne muscular dystrophy (DMD), DMD together with glycerol kinase (GK) deficiency, or DMD together with both GK deficiency and congenital adrenal hypoplasia (AHC). Analysis of deletions in these patients allows the mapping of these mutations in Xp21. The following order is proposed: Xpter - L1 - AHC - GK - DMD - Xcen. One of the boys with DMD, GK, and AHC is shown by pulsed-field-gel electrophoresis to have a deletion which has a proximal endpoint at least 500 kb distal from the pERT87 (DXS164) locus.

Acid Phosphatase↗

Molecular analysis of muscular dystrophy.

It is now possible to map almost any disease locus to a chromosomal region in the human genome by family studies with restriction fragment length polymorphisms. Duchenne and Becker muscular dystrophies have been shown to be localized within the same small region of Xp21 on the human X chromosome. Myotonic dystrophy has been localized to a region close to the centromere of chromosome 19. Technologies are now available to identify candidate genes for the diseases. Autosomal recessive muscular dystrophies are more difficult to study, but even these will be amenable to analysis in the very near future. The next decade should witness some exciting advances in the molecular analysis and clinical management of human muscular dystrophies.

Chromosome Mapping↗

Mapping of a cerebellar degeneration related protein and DXS304 around the fragile site.

We have localized the gene encoding a cerebellar degeneration related (CDR) protein to a region proximal to the fragile site close to DXS98 and DXS105. This gene is polymorphic with the enzyme RsaI and therefore also provides a new genetic marker in this region. We have refined the localization of the locus DXS304 distal to the breakpoint in a patient suffering from Hunter disease. This confirms the localization of DXS304 distal to the fragile site previously suggested by linkage studies and localizes the fragile X mutation to a relatively small region between the Hunter breakpoint and the breakpoint in another hybrid B17.

Base Sequence↗