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Biomedical subjects

A E Hughes

Publications and source records attributed to A E Hughes.

At least 19 recordsLinked to original sources
PubMed1996

Localisation of a gene for central areolar choroidal dystrophy to chromosome 17p.

Central areolar choroidal dystrophy (CACD) is a rare inherited retinal disease which causes progressive profound loss of vision in patients during their 4th decade. We have identified a Northern Irish family with 19 affected individuals in three living generations. We have performed a total genome search and established linkage of CACD in this family to chromosome 17p (multipoint Zmax = 5.65 at D17S938). The genes for phosphatidylinositol transfer protein (PITPN), retinal guanylate cyclase (GUC2D), beta-arrestin 2 (ARRB2), pigment epithelium-derived factor (PEDF) and recoverin (RCV1) map to this region and are candidate genes for retinal disease. Analysis of the coding region of the PITPN gene failed to reveal any mutation in this family.

Arrestins↗
PubMed1996

Association of two loci on chromosome 2q with nodal osteoarthritis.

OBJECTIVE: To search for genetic association between microsatellite marker loci and sibling pairs with nodal osteoarthritis (NOA). METHODS: Using the affected sibling pair method of analysis, genomic DNA from 66 sib pairs with NOA was analysed for association with highly polymorphic microsatellite marker loci. The microsatellite markers were amplified using polymerase chain reaction and typed on polyacrylamide gels. RESULTS: A significant association (p < 0.05) was identified between NOA and two loci on the short arm of chromosome 2 (2q 23-35). Candidate genes for osteoarthritis in this region include: fibronectin, a glycoprotein present in the extracellular matrix of normal cartilage; the alpha 2 chain of collagen type V, a major constituent of bone; and the interleukin-8 receptor, important in the regulation of neutrophil activation and chemotaxis. CONCLUSIONS: The chromosomal region 2q 23-35 requires further detailed study in NOA. Confirmation of these findings in large independent data sets and further analysis of candidate genes in this region will be important in unravelling the molecular basis for this common disease.

Adult↗
PubMed1996

A molecular variant of angiotensinogen is associated with diabetic nephropathy in IDDM.

Recent studies have suggested that an inherited predisposition to essential hypertension may increase susceptibility to nephropathy for patients with IDDM. Essential hypertension has been linked to the angiotensinogen (AGT) gene in genetic linkage studies in American and European populations. A molecular variant (M235T), which has a functional effect, has been described with highest plasma AGT levels being associated with the TT genotype. In a case-control study, we have evaluated the role of this functional genetic marker in patients with IDDM and nephropathy and in IDDM patients without nephropathy. We studied 195 IDDM patients, of whom 95 had established diabetic nephropathy; the remaining 100 patients, who had no evidence of microalbuminuria, served as control subjects. All patients were whites born in Northern Ireland. The point mutation in the AGT gene was analyzed using restriction typing. The background frequency of the M235T variant was assessed in 80 healthy blood donors, and the TT genotype was present in 9%. This genotype occurred in 8% of control IDDM patients without nephropathy and 19% of IDDM patients with nephropathy (P = 0.025). The odds ratio for diabetic nephropathy associated with the TT genotype was 2.7 (95% CI 1.04-7.52). There was no relationship between blood pressure and AGT genotypes in the control group. We cannot exclude the possibility that the observed association in the nephropathy group is due to an association between AGT genotype and hypertension. This evidence may help to explain the predisposition to diabetic nephropathy afforded by hypertension and merits further investigation.

Adult↗
PubMed1995

Localisation of a gene for chondrocalcinosis to chromosome 5p.

Chondrocalcinosis is a common disorder which may associate with acute and chronic arthritis. A familial form, inherited as an autosomal dominant trait, has been mapped in a large family in which affected members also suffer recurrent fits in childhood. The gene which causes this disease shows linkage with several polymorphic markers on chromosome 5p with a maximum multipoint lod score of 4.6 between D5S810 and D5S416. Mapping a locus for chondrocalcinosis will allow the heterogeneity of the disorder to be assessed and may also be relevant to understanding the aetiology of osteoarthritis with which it commonly associates.

Child↗
PubMed1994

ACE gene typing.

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Cardiovascular Diseases↗
PubMed1994

Is genetic predisposition an important risk factor in age-related macular degeneration?

Age-related macular degeneration (ARMD) is the most common cause of visual morbidity in the aged in the Western world. The aetiology of ARMD is unknown. Although clinicians have noted that ARMD demonstrates a familial tendency, the question regarding the role of hereditary factors in ARMD remains unanswered. The aims of this study were to assess the level of genetic input into ARMD and to assess the mode of inheritance of the disease. Fifty affected patients and 50 age- and sex-matched controls and their immediate families were invited to take part in the study. Thirty-six patients, controls and their families were studied. Eighty-one siblings of affected patients and 78 control siblings were available. Twenty of the 81 affected siblings were found to suffer from ARMD. In contrast only 1 of 78 control siblings had ARMD. This was statistically significant. The results confirm that hereditary factors are important in the aetiology of ARMD.

Disease Susceptibility↗
PubMed1994

A gene for Waardenburg syndrome type 2 maps close to the human homologue of the microphthalmia gene at chromosome 3p12-p14.1.

Waardenburg syndrome (WS), an autosomal dominant syndrome of hearing loss and pigmentary disturbances, comprises at least two separate conditions. WS type 1 is normally caused by mutations in PAX3 located at chromosome 2q35 and is distinguished clinically by minor facial malformations. We have now located a gene for WS type 2. Two families show linkage to a group of microsatellite markers located on chromosome 3p12-p14.1. D3S1261 gave a maximum lod score of 6.5 at zero recombination in one large Type 2 family. In a second, smaller family the adjacent marker D3S1210 gave a lod of 2.05 at zero recombination. Interestingly, the human homologue (MITF) of the mouse microphthalmia gene, a good candidate at the phenotypic level, has recently been mapped to 3p12.3-p14.4.

Animals↗
PubMed1994

Genetic linkage of familial expansile osteolysis to chromosome 18q.

Familial expansile osteolysis is a rare bone dysplasia which is transmitted as an autosomal dominant trait in a large kindred in Northern Ireland. The gene which causes the disease shows tight linkage with several polymorphic markers on chromosome 18q with a maximum lod score of 11.53 at a recombination fraction of 0.00 with D18S64. The gene is flanked by D18S35 and D18S61 and is located at chromosome 18q21.1-q22. Mapping a new locus for a gene involved in regulation of bone metabolism may also have implications in the study of Paget's disease of bone which is a common related bone dysplasia.

Animals↗
PubMed1994

Hereditary caeruloplasmin deficiency, dementia and diabetes mellitus.

We report two brothers with complete caeruloplasmin deficiency. The brothers presented with dementia and diabetes mellitus. Twelve relatives have partial caeruloplasmin deficiency. There is no copper overload. Transmission is autosomal recessive. DNA analysis showed genetic linkage between the deficiency and various polymorphic markers flanking the caeruloplasmin gene on chromosome 3q25. This is consistent with a mutation of the caeruloplasmin gene. Caeruloplasmin catalyses the oxidation of ferrous iron to ferric iron. Both brothers have low serum iron and increased liver iron. The index patient was given caeruloplasmin-containing, fresh-frozen plasma. A dose of 2.6 mg caeruloplasmin increased serum iron from 5 microM/l to 10 microM/l. A dose of approximately 72 mg increased serum iron from 5 microM/l to 19 microM/l. The abnormal serum and liver iron levels, and the caeruloplasmin-induced rise in serum iron, confirm a previous suggestion that caeruloplasmin maintains the normal rate of flow of iron from store to transferrin. Dementia and diabetes mellitus have been described in only one other homozygote. The absence of copper overload, and the linkage of the deficiency with chromosome 3q25, distinguish this condition from Wilson's disease.

Brain↗
PubMed1993

Extracellular protein secretion of cultured normal and Pagetic osteoblasts.

Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has been used to map the extracellular secretory activity of normal osteoblasts. The proteins osteonectin, bone sialoprotein, and both the C-telopeptide of collagen I together with collagen I have now been positionally identified. In addition the secretory differences which exist between normal and Pagetic osteoblasts have been mapped with the Pagetic osteoblasts shown to consistently secrete an altered 30 kDa C-telopeptide of collagen type I. The use of the diphosphonate Pamidronate in the treatment of Paget's disease of bone has beneficial effects with suppression of the bone isoenzyme marker alkaline phosphatase. It has been reported that diphosphonates directly inhibit human osteoblast secretory function as well as osteoclast metabolism. The effects of Pamidronate on the secretory activity of normal and Pagetic osteoblast cultures was also investigated. The extracellular protein secretion of normal and Pagetic osteoblasts was not affected by Pamidronate treatment as assessed by 2-D PAGE. This technique allows a comprehensive multiparameter assessment of extracellular secretory activity in normal and diseased states. The findings show that the Pagetic osteoblasts cultured in vitro are functionally abnormal and they support the hypothesis that the underlying problem in Paget's disease is characterised by disorder of osteoblast and osteoclast interactions.

Aged↗
PubMed1993

Optimization of microsatellite analysis for genetic mapping.

A method for typing microsatellite polymorphisms is described. It involves amplification using the polymerase chain reaction with one primer 5' end-labeled with 32P. Alleles are separated by denaturing gel electrophoresis and detected by autoradiography. Standardized conditions allow accurate typing of almost all microsatellite polymorphisms, and results are usually obtained within 24 h.

Autoradiography↗
PubMed1993

Autosomal dominant polycystic kidney disease with minimal clinical expression unlinked to the PKD1 locus.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations at the PKD1 locus in most families. This locus has been assigned to the short arm of chromosome 16 by linkage analysis. It has been estimated that approximately 5% of families have a disease that does not map to this locus and most of these families have clinical features indistinguishable from the disease caused by PKD1 mutations. We report a large three-generation Caucasian family from Northern Ireland with ADPKD in whom all affected individuals (age range 22-68) were normotensive and only the two eldest had mild renal impairment. Linkage was excluded between the disease and both the alpha-globin gene complex and the microsatellite marker D16S283. This family confirms that phenotypic heterogeneity exists between unlinked families and that certain non-PKD1 mutations cause mild disease expression. Many such individuals may therefore remain undetected and the incidence of families with ADPKD who have non-PKD1 mutations may be greater than previously estimated.

Adolescent↗
PubMed1993

Genetic linkage analysis, clinical features and prognosis of autosomal dominant polycystic kidney disease in Northern Ireland.

Fifteen families with autosomal dominant polycystic kidney disease were analysed for coinheritance of the disease and DNA markers flanking the PKD1 locus. Eleven families demonstrated linkage to PKD1 markers. Two families were unlinked to the PKD1 locus (non-PKD1) and in two families the markers were uninformative. The clinical features and prognosis of 49 subjects with a PKD1 genotype were compared with 17 non-PKD1 subjects. The age at diagnosis in non-PKD1 subjects (37 +/- 11 years) was significantly later than PKD1 subjects (25 +/- 13 years, p < 0.001). Only two (12%) non-PKD1 subjects presented initially with clinical features of autosomal polycystic kidney disease compared to 27 (55%) of PKD1 subjects (p < 0.002). Hypertension was more common in PKD1 compared to non-PKD1 subjects (29% vs. 12%), as was stage renal failure (25% vs. 6%). Seventy-five percent of non-PKD1 subjects had not developed end-stage renal failure by the age of 54 years compared to only 35% of PKD1 subjects. Most families with autosomal polycystic kidney disease in this population have disease due to mutations at the PKD1 locus. However, the proportion of non-PKD1 families appears to be higher than estimates for other populations. This study also confirms initial reports that subjects with a non-PKD1 genotype have a milder disease with a better prognosis than those with a PKD1 genotype.

Adult↗
PubMed1992

Two-dimensional polyacrylamide gel electrophoresis reveals differences between osteoblast and fibroblast extracellular proteins.

Normal human skin fibroblast primary cell lines secrete over 50 proteins into culture medium. These have been mapped previously using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and this technique has now been used to investigate extracellular protein secretion by human osteoblasts in vitro. We report the mapping of a number of consistent markers specific to the osteoblast. In particular, one protein chain with posttranslational modifications was found to be unique to the osteoblast extracellular protein map. The absence of the N- and O-glycoforms of collagenase from the osteoblast profile in this study concurs with findings reported using the immunoprecipitation functional assay and Northern blot analysis. The use of 2-D PAGE in phenotypic assessment provides a more complete analysis than the standard range of single-parameter tests for osteoblasts. Mapping of extracellular and cellular proteins in addition to bone matrix protein analysis will allow a comprehensive analysis of normal osteoblast function. This technique may also be applied to the study of osteoblasts in relation to bone disease and in assessing the phenotypic shift within a normal osteoblast culture.

Cells, Cultured↗
PubMed1992

Linkage of epidermolysis bullosa simplex to keratin gene loci.

Epidermolysis bullosa simplex (EBS) is an autosomal dominant disorder characterised by intraepidermal blistering of the skin. Two families with Weber-Cockayne EBS have been analysed for linkage to keratin gene loci. In the first family, linkage was found to chromosome 17 markers flanking the keratin 14 gene (D17S74: Zmax = +2.45, theta = 0.10; COL1A1: Zmax = +0.97, theta = 0.00) and markers near the keratin 5 gene on chromosome 12 were excluded (D12S17: Z less than -2.0, theta = 0.08; COL2A1: Z less than -2.0, theta = 0.13). In contrast, the second family showed linkage to the region containing the keratin 5 gene (D12S17: Zmax = +1.37, theta = 0.08; COL2A1: Zmax = +0.33, theta = 0.15) and was not linked to the keratin 14 gene (D17S74: Z less than -2.0, theta = 0.14). The Weber-Cockayne form of EBS is genetically heterogeneous with linkage to different keratin gene loci.

Blotting, Southern↗