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M A Aldred

Publications and source records attributed to M A Aldred.

25 records · Page 2Linked to original sources
PubMed1994

Heterogeneity analysis in 40 X-linked retinitis pigmentosa families.

Analysis of genetic heterogeneity in 40 kindreds with X-linked retinitis pigmentosa (XLRP), with 20 polymorphic markers, showed that significant heterogeneity is present (P = .001) and that 56% of kindreds are of RP3 type and that 26% are of RP2 type. The location of the RP3 locus was found to be 0.4 cM distal to OTC in the Xp21.1 region, and that of the RP2 locus was 6.5 cM proximal to DXS7 in Xp11.2-p11.3. Bayesian probabilities of linkage to RP2, RP3, or to neither locus were calculated. This showed that 20 of 40 kindreds could be assigned to one or the other locus, with a probability > .70 (14 kindreds with RP3 and 6 kindreds with RP2 disease). A further three kindreds were found to be unlinked to either locus, with a probability > .8. The remaining 17 kindreds could not be classified unambiguously. This highlights the difficulty of classifying families in the presence of genetic heterogeneity, where the two loci are separated by an estimated 16 cM.

Bayes Theorem↗
PubMed1993

Linkage analysis in a family with complete type congenital stationary night blindness with and without myopia.

A family is described with X-linked congenital stationary night blindness of the complete type (CSNB1) in which clinical variation between affected males resulted in diagnostic difficulties. In two affected male cousins, one had congenital nystagmus and myopia, while the other was initially thought to have retinitis pigmentosa with optic atrophy and was hyperopic. The diagnosis of X-linked congenital stationary night blindness was established by clinical, psychophysical and electrophysiological criteria, and DNA markers flanking the CSNB1 locus were analysed in the family. The results show that both affected males have inherited the same haplotype from their carrier mothers, excluding the possibility that a myopia gene in linkage disequilibrium with CSNB1 has recombined with this locus.

Adolescent↗
PubMed1992

Linkage analysis in X-linked congenital stationary night blindness.

X-linked congenital stationary night blindness (XL-CSNB) is a nonprogressive disorder of the retina, characterized by night blindness, reduced visual acuity, and myopia. Previous studies have localized the CSNB1 locus to the region between OTC and TIMP on the short arm of the X chromosome. We have carried out linkage studies in three XL-CSNB families that could not be classified as either complete or incomplete CSNB on the criteria suggested by Miyake et al. (1986. Arch. Ophthalmol. 104: 1013-1020). We used markers for the DXS538, DMD, OTC, MAOA, DXS426, and TIMP loci. Two-point analyses show that there is close linkage between CSNB and MAOA (theta max = 0.05, Zmax = 3.39), DXS426 (theta max = 0.06, Zmax = 2.42), and TIMP (theta max = 0.07, Zmax = 2.04). Two multiply informative crossovers are consistent with CSNB lying proximal to MAOA and distal to DXS426, respectively. Multipoint analysis supports this localization, giving the most likely order as DMD-17 cM-MAOA-7.5 cM-CSNB-7.5 cM-DXS426/TIMP-cen, and thus refines the localization of CSNB.

Female↗
PubMed1991

Genetic localisation of the RP2 type of X linked retinitis pigmentosa in a large kindred.

Genetic linkage and deletion studies have led to the proposal that there are at least two loci on the X chromosome which are responsible for X linked retinitis pigmentosa (XLRP). One locus (RP3) has been closely defined by genetic linkage and deletion analyses and localised to the region between the ornithine transcarbamylase (OTC) and chronic granulomatous disease (CYBB) loci in Xp21.1-p11.4. The other locus (RP2) has been assigned by linkage analysis alone to region Xp11.4-p11.2, but its localisation is less well defined. The results of a multipoint linkage analysis of a single large XLRP kindred using eight informative loci provide further evidence on the localisation of RP2 to this region. The maximum likelihood location of this locus shows a multipoint lod score of 7.17 close to DXS255 (in Xp11.22) and TIMP (in Xp11.3-p11.23), neither of which show recombination with RP2, in an area extending from 2 cM proximal to DXS7 to 1 cM distal to DXS14 (approximate 95% confidence limits).

Bayes Theorem↗