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Biomedical subjects

B Jay

Publications and source records attributed to B Jay.

At least 37 records · Page 2Linked to original sources

Prenatal diagnosis of X-linked choroideremia with mental retardation, associated with a cytologically detectable X-chromosome deletion.

We describe a family in which an X-chromosome deletion is segregating with choroideremia, and X-linked recessive condition. The DNA sequences DXYS1 and DXS3, defined by the probes pDP34 and 19.2 respectively, are absent in the affected male (who is also mentally retarded), and hemizygous in his mother and in his carrier sister, who presented early in pregnancy. Analysis of chorionic villus DNA formed the basis of prenatal exclusion of choroideremia in her male fetus. In three female relatives, studied with late-labelling techniques, the deleted X was preferentially inactivated in 86-100% of cells studied. This family confirms the localisation of the choroideremia locus to within Xq13----21, and places the loci for anhidrotic ectodermal dysplasia and the X-linked immunodeficiencies outside this region.

Choroid

Molecular genetic approaches to the analysis of human ophthalmic disease.

In this review of the recent literature, the contribution that the new techniques of molecular genetics has made in the analysis and diagnosis of human ophthalmic conditions is presented and discussed. Among the disorders reviewed are X-linked retinitis pigmentosa, Norrie's disease, gyrate atrophy and retinoblastoma, and there are also sections on crystallins and visual pigments.

Chromosome Mapping

Linkage relationships between X-linked retinitis pigmentosa and nine short-arm markers: exclusion of the disease locus from Xp21 and localization to between DXS7 and DXS14.

Linkage data between X-linked retinitis pigmentosa (XLRP) and nine X-chromosomal markers are reported. To test the assignment of XLRP to the Xp21 region (as considered at Human Gene Mapping 8), an analysis of XLRP and six markers flanking this region was undertaken. The XLRP locus was found to be excluded from the chromosome distal to ornithine transcarbamylase (OTC) (P = 6.5 X 10(-5]. Further data were accumulated with three more probes proximal to DXS7 (L1.28), the closest linked probe. Multipoint analysis of these data suggests a posterior probability of .94 that XLRP is proximal to DXS7 (L1.28), which has been mapped to the region Xp11.3.

Chromosome Mapping

A genetic linkage study of choroideremia.

One hundred and twenty-two members of 15 choroideremia families have been used in a genetic linkage study of choroideremia (TCD) using four DNA probes situated on the X chromosome. Linkage was analysed using DNA probes DXS14 (p58-1), DXYS1 (pDP 34), DXS178 (p212) and DXS177 (lambda 2.7). Statistically significant linkage was demonstrated with DXYS1 (theta = 0.00, lod 4.95), in agreement with the findings of Nussbaum et al. (1985). Evidence consistent with loose linkage to TCD was also found with DXS14 (theta = 0.31, lod 0.23), DXS178 (theta = 0.18, lod 1.41) and DXS177 (theta = 0.27, lod 0.20). The results suggest that TCD is located in the region Xq13-q21. Probe DXYS1 is likely to prove useful in the prenatal diagnosis of this condition.

Choroid

Plasma 5-S-cysteinyldopa concentrations in oculocutaneous albinism.

5-S-cysteinyldopa concentrations were determined by high-pressure liquid chromatography and electrochemical detection in plasma from normally pigmented patients and patients with oculocutaneous albinism, both tyrosinase-positive and tyrosinase-negative. The plasma 5-S-cysteinyldopa concentrations were similar in all three groups, suggesting that 5-S-cysteinyldopa can be produced by mechanisms which do not involve tyrosinase.

Albinism

X-linked retinal disorders and the Lyon hypothesis.

The heterozygous states in X-linked ocular albinism, choroideremia and X-linked retinitis pigmentosa are described. Their fundus appearances differ, to a greater or lesser extent, from those of hemizygous (affected) males and a possible explanation for these differences is briefly discussed.

Adult

X-linked ocular albinism: a family containing a manifesting heterozygote, and an affected male married to a female with autosomal recessive ocular albinism.

A pedigree of X-linked ocular albinism is presented containing nine affected males and 10 heterozygous females. One carrier female showed ocular changes similar to those of affected males. She is considered to be a manifesting heterozygote, a situation explained by the Lyon hypothesis. One affected male married a female with autosomal recessive ocular albinism and produced one daughter with the fundus changes of the carrier state of X-linked ocular albinism, and one son with normal eyes. The daughter did not show any evidence of the additive effect of the two different genes for X-linked and autosomal recessive ocular albinism.

Albinism

Albinism. Recent advances.

There have recently been several fundamental advances in our understanding of albinism, both in animals and in man. These advances have been in the division of oculocutaneous albinism into tyrosinase-negative and tyrosinase-positive forms, the demonstration of a widespread disturbance in the structure of melanosomes in X-linked ocular albinism, the description of the condition now known as autosomal recessive ocular albinism, and a peculair anatomical abnormality of the visual pathways which appears to be present in all forms of oculocutaneous and ocular albinism. Evidence has been presented which confirms that the retinogeniculate anomaly in human albinos is similar to that in animals, and it has recently been suggested that there may be two major patterns of geniculocortical projected in man, as there are in the Siamese cat.

Albinism

Prevention of blindness from retinitis pigmentosa.

Prevention of blindness from retinitis pigmentosa is considered in three stages: what can be done at present; what is likely to be achieved within the next few years; and what can be envisaged for the more distant future.

Blindness

Human albinism.

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Albinism