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Biomedical subjects

A T Moore

Publications and source records attributed to A T Moore.

At least 109 records · Page 6Linked to original sources

Genetic mapping of the Kallmann syndrome and X linked ocular albinism gene loci.

The X linked form of Kallmann syndrome (KAL) and X linked ocular albinism (OA1) have both been mapped to Xp22.3. We have used a dinucleotide repeat polymorphism at the Kallmann locus to type 17 X linked ocular albinism families which had previously been typed for the Xg blood group (XG) and the DNA markers DXS237 (GMGX9), DXS143 (dic56), and DXS85 (782). Close linkage was found between KAL and OA1 with a maximum lod score (Zmax) of 30.14 at a recombination fraction (theta max) of 0.06 (confidence interval for theta: 0.03-0.10). KAL was also closely linked to DXS237 (Zmax = 15.32; theta max = 0.05; CI 0.02-0.12) and DXS143 (Zmax = 14.57; theta max = 0.05; CI 0.02-0.13). There was looser linkage to the Xg blood group (XG) and to DXS85 (782). Multipoint linkage analysis gave the map: Xpter-XG-0.13-DXS237-0.025-KAL-0.025-DXS143-0.01 5-OA1-0.09-DXS85-Xcen. Placement of OA1 proximal to DXS143 was supported by odds of 2300:1 compared to other orders. This confirms our previous localisation of OA1 and improves the genetic mapping of both disease loci.

Albinism↗

Evaluation of molecular genetic diagnosis in the management of familial adenomatous polyposis coli: a population based study.

A population based clinical and molecular genetic study of familial adenomatous polyposis coli (FAPC) was performed to investigate the value of molecular genetic analysis and ophthalmological assessment in the presymptomatic diagnosis of FAPC. The point prevalence of affected patients was 2.62 x 10(-5) (1/38,000) and the minimum heterozygote prevalence was estimated at 3.8 x 10(-5) (1/26,000). Eight of 33 (24%) probands were new mutations. Forty-eight asymptomatic relatives at 50% prior risk aged between 10 and 40 years were assessed for risk modification with linked DNA markers: in nine subjects (18%) the family structure was unsuitable for linkage based analysis, but 32 subjects were informative with a panel of intragenic and closely linked markers (25 had a combined age/DNA related risk of < 1% (low risk group) and seven were at high risk (DNA predicted risk > 99%)). Ophthalmological assessment for CHRPEs showed that 27/43 (63%) affected patients and high risk relatives and 0/18 low risk relatives had more than three CHRPEs. Interfamilial variation in CHRPE expression was apparent. This study has shown that DNA based risk modification with intragenic and closely linked DNA markers is informative in most FAPC families. In addition to the clinical benefits of presymptomatic diagnosis for FAPC, the reduction in screening for low risk relatives (365 person years in the present study) means that molecular genetic diagnosis of FAPC is a cost effective procedure.

Adenomatous Polyposis Coli↗

Results of early surgery for infantile esotropia in normal and neurologically impaired infants.

A prospective study was performed over a 4-year period of 56 infants presenting with infantile esotropia to assess development of binocularity after surgical alignment before 2 years of age. In 50% of cases infantile esotropia was associated with neurological problems or prematurity. Forty-three cases have undergone surgery (mean age 15.7 months +/- 3.46); 86% were aligned (+/- 10 dioptres) at 2 years. Eighty-seven per cent of normal children and 74% of children with neurological problems or prematurity were aligned at last follow-up (mean 27.2 months since surgery). Tests of fusion and stereopsis have to date been possible upon 21 'successfully' aligned infants and although most have evidence of peripheral sensory fusion none showed stereopsis to more than one test. Although early surgery achieves a good cosmetic result in normal children and those with neurological problems, our findings question its ability to promote the development of even gross stereopsis in most children.

Depth Perception↗

Genetic counselling in X-linked ocular albinism: clinical features of the carrier state.

Forty-nine obligate heterozygotes and 64 at risk females were assessed from 17 families affected by X-linked ocular albinism to determine the relative values of clinical examination and skin biopsy in carrier detection. 92% of obligate heterozygotes had a mud-splattered appearance of the fundus with hyperpigmented streaks and in 74% this was associated with marked iris translucency. Skin histology showed macromelanosomes in 84%. 27 of 64 (42%) at risk females had definite features of the carrier state and 19 (30%) were unequivocally normal but a further 18 (28%) had mild RPE abnormalities, often with iris transillumination defects, of uncertain significance. Fundus examination will detect most carrier females but will not allow reliable genetic counselling for all at risk females, even when supplemented by skin biopsy.

Albinism, Ocular↗

Bilateral optic nerve sheath meningiomas in a patient with neurofibromatosis type 2.

A 34-year-old woman who presented with hearing loss and tinnitus was found to have reduced vision bilaterally. Computed tomography scan revealed bilateral acoustic neuromas and bilateral optic nerve sheath meningiomas. The presence of bilateral acoustic neuromas fulfils the criteria for the diagnosis of central neurofibromatosis (neurofibromatosis type 2). Although this is the first report of bilateral optic nerve sheath meningioma in neurofibromatosis type 2, meningiomas are commoner in this dominantly inherited disorder, than in its absence and both forms of central nervous system tumour may be caused by loss of tumour suppressor genes on chromosome 22.

Adult↗

Abnormal dark adaptation kinetics in autosomal dominant sector retinitis pigmentosa due to rod opsin mutation.

The time course of dark adaptation was measured in 10 subjects from three families with autosomal dominant sector retinitis pigmentosa (RP) due to mutations in the first exon of the rod opsin gene. In each subject cone adaptation and the early part of the recovery of rod sensitivity followed the normal time course, but the later phase of rod adaptation was markedly prolonged. The recovery of rod sensitivity is much slower than that reported in any other outer retinal dystrophy. Using a model based upon primate data of rod outer segment length and turnover, we have calculated that the delayed phase of the recovery of rod sensitivity in the RP patients tested following strong light adaptation could be due in part to formation of new disc membrane with its normal concentration of rhodopsin rather than in situ regeneration of photopigment.

Adolescent↗

Genetic mapping of X linked ocular albinism: linkage analysis in British families.

Genetic linkage studies were performed in 16 British families affected by X linked ocular albinism (XLOA) using RFLPs from the Xp22.3 region. Linkage was confirmed between the XLOA locus (OA1) and the loci DXS143 (dic56; Zmax = 15.90 at theta = 0.0, confidence interval (CI) 0-0.035), DXS85 (782; Zmax = 15.67 at theta = 0.04, CI = 0.007-0.11), and DXS237 (GMGX9; Zmax = 12.65 at theta = 0.08, CI = 0.03-0.17). Multipoint linkage analysis placed OA1 between DXS85 (782) and DXS237 (GMGX9) with odds exceeding 10(4):1 to give the map DXS85-(OA1,DXS143)-DXS237-XG-Xpter. OA1 lies close to DXS143 (dic56) but in the absence of recombinants the order of these loci could not be determined.

Albinism, Ocular↗

Incidence and significance of congenital hypertrophy of the retinal pigment epithelium (CHRPE) in familial adenomatous polyposis coli (FAPC).

As part of a population based study of familial colorectal cancer 33 affected patients with familial adenomatous polyposis coli (FAPC) and 33 relatives, at 50% risk of inheriting FAPC, from 24 kindreds, were identified and examined. Fourteen of the affected patients had extracolonic manifestations of the FAPC gene. Twenty-five of the 33 affected patients had one or more areas of congenital hypertrophy of the retinal pigment epithelium (CHRPE) and 20 had more than three CHRPEs, all having bilateral lesions. There were significant interfamilial differences in the ocular findings. Because of this interfamilial difference in the predisposition to develop CHRPEs it is important to establish the CHRPE status of individual FAPC families before the results of ophthalmoscopy can be used to predict the carrier status of at risk relatives.

Adenomatous Polyposis Coli↗

Ophthalmological screening for von Hippel-Lindau disease.

Forty seven individuals (from 16 kindreds) without prior evidence of retinal haemangiomas underwent full ophthalmological assessment as part of a comprehensive screening programme for Von Hippel-Lindau disease. Ten were known to be affected on the basis of non-ocular involvement and 37 were at 50% risk of having the abnormal gene. Seventeen angiomas were detected in 14 individuals (six affected patients and eight at risk relatives). Regular detailed ophthalmological assessment is important for all patients with von Hippel-Lindau disease and for relatives at risk of inheriting the abnormal gene.

Adult↗

Extracapsular cataract surgery with lens implantation in diabetics with and without proliferative retinopathy.

In a retrospective study we have examined all diabetics (66 operated eyes) and an equal number of non-diabetic matched controls who underwent extracapsular cataract extracation (ECCE) with intraocular lens (IOL) implantation over a two-year period ending in December 1987. Of the diabetic patients' 76% eyes improved by at least two lines of Snellen acuity postoperatively. Of these patients 68% eyes and of the control eyes 83% achieved an acuity of 6/12 or better. In the diabetics the visual outcome depended on the state of the retinopathy and in particular the maculopathy. The diabetic group had a greater incidence of postoperative inflammation, but the major complications were related to continuing neovascularisation. Early postoperative laser photocoagulation may help to prevent these proliferative complications, and, provided a large, adequate capsulotomy is performed for capsular thickening, the presence of an IOL does not interfere with this photocoagulation. We also advise early postoperative assessment, and treatment if necessary, of any maculopathy. Diabetic retinopathy should no longer be regarded as a contraindication to intraocular lens insertion.

Adult↗

Flecked retina associated with ring 17 chromosome.

We report the case of a mentally retarded male with a ring 17 chromosome who had subretinal drusen-like deposits in each eye. This is the second report of flecked retina in a patient with ring 17 chromosome, suggesting that there may be a causal relationship between abnormalities of chromosome 17 and retinal pigment epithelial or photoreceptor dysfunction.

Adult↗

Structure of Lisch nodules in neurofibromatosis type 1.

Postmortem examination of the eyes of a patient with neurofibromatosis Type I was performed by light and electronmicroscopy. Lisch nodules were examined and found to consist of a condensation of spindle cells on the anterior iris surface. When nodules were pigmented an underlying stromal naevus was present. Lisch nodules are confirmed as being of melanocytic origin.

Humans↗

Ocular enlargement following infantile corneal opacification.

Congenital hereditary endothelial dystrophy (CHED) is not generally thought to be associated with other ocular abnormalities. Ultrasonography in a series of twenty eyes (ten patients) with CHED shows ocular enlargement similar to that occurring in uncomplicated axial myopia. There was an inverse relationship between the degree of enlargement and the visual acuity or visual result following penetrating keratoplasty suggesting that infantile corneal oedema sufficient to cause stimulus deprivation may result in abnormal enlargement of the globe.

Adolescent↗

Clinical features and natural history of von Hippel-Lindau disease.

The clinical features, age at onset and survival of 152 patients with von Hippel-Lindau disease were studied. Mean age at onset was 26.3 years and 97 per cent of patients had presented by aged 60 years. Retinal angioma was the first manifestation in 65 patients (43 per cent), followed by cerebellar haemangioblastoma (n = 60, 39 per cent) and renal cell carcinoma (n = 15, 10 per cent). Overall, 89 patients (59 per cent) developed a cerebellar haemangioblastoma, 89 (59 per cent) a retinal angioma, 43 (28 per cent) renal cell carcinoma, 20 (13 per cent) spinal haemangioblastoma and 11 (7 per cent) a phaeochromocytoma. Renal, pancreatic and epididymal cysts were frequent findings but their exact incidence was not accurately assessed. Mean age at diagnosis of renal cell carcinoma (44.0 +/- 10.9 years) was significantly older than that for cerebellar haemangioblastoma (29.0 +/- 10.0 years) and retinal angioma (25.4 +/- 12.7 years). The probability of a patient with von Hippel-Lindan disease developing a cerebellar haemangioblastoma, retinal angioma or renal cell carcinoma by age 60 years was 0.84, 0.7 and 0.69, respectively. A comprehensive screening protocol for affected patients and at-risk relatives is presented, based on detailed analysis of age at onset data for each of the major complications. Median actuarial survival was 49 years, with renal cell carcinoma the leading cause of death.

Adrenal Gland Neoplasms↗