Biomedical subjects
P J Morrison
Publications and source records attributed to P J Morrison.
Screening for breast cancer, time to think--and stop?
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The hyperstethoscope syndrome.
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The epidemiology of Huntington's disease in Northern Ireland.
A survey of Huntington's disease (HD) in Northern Ireland, with a population of 1.5 million, has shown a 1991 prevalence rate of 6.4/100,000. Virtually complete ascertainment was achieved, enabling prevalence rate estimates and age statistics to be calculated over the last 20 years. The prevalence rate is similar to the high prevalence rates of HD found in most European populations, suggesting the presence of either one extremely ancient or a number of separate mutational origins, resulting in a uniform European HD prevalence. The ages at diagnosis and duration of the disease are similar to previous studies, suggesting a consistent effect of the HD gene in all families. Estimates of heterozygote frequency (HF), direct and indirect mutation rate, fertility, and genetic fitness (W) were made. Reliable HF estimates gave values between 10 and 11 x 10(-5). The direct and indirect mutation rates were 0.32 x 10(-6) and 1.05 x 10(-6) respectively. W was increased in the affected HD population but decreased in the at risk population. Fertility in HD is not reduced, but it appears that at risk patients have actively limited their family size. Factors responsible include, among others, the fear of developing HD and genetic counselling of families. This is the first published epidemiological survey to include ascertainment data in a population both before and after isolation of the HD gene, and with the diagnosis in virtually all patients confirmed by DNA mutation testing.
Serum iron, total iron binding capacity and ferritin in early Huntington disease patients.
Serum iron, total iron binding capacity and ferritin was estimated in 42 patients with early Huntington disease (HD) and in 148 matched controls. Ferritin levels were significantly low in affected male subjects as compared to controls. Iron levels and total iron binding capacity were normal in HD patients. The importance of this finding, that occurs early in the pathogenesis of HD, is unknown.
Who should check our tools?
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Images in Clinical Medicine: Peutz-Jeghers syndrome.
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Trinucleotide repeat repeat repeat.
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Pharmacokinetics of rufloxacin in patients with impaired renal function.
The pharmacokinetics of rufloxacin were investigated in normal subjects and in patients with various degrees of renal failure after the administration of a single oral 400-mg dose. Twenty-four subjects were classified by glomerular filtration rate (GFR) normalized for body surface area. Group 1 subjects had GFRs of > 80 ml/min, group 2 subjects had GFRs from 30 to 80 ml/min, group 3 subjects had GFRs from 8 to 29 ml/min, and group 4 subjects had GFRs of < 8 ml/min. The patients in group 4 were on continuous peritoneal dialysis or underwent hemodialysis 48 h after dosing. Plasma and urinary rufloxacin concentrations were determined by high-performance liquid chromatography. A two-compartment model was used to calculate rufloxacin pharmacokinetic parameters. Apparent total body clearance of the drug was linearly related to GFR (r = 0.696; P < 0.01). The elimination half-life increased proportionally with the severity of renal impairment, with values of 30 +/- 3, 36 +/- 5, and 44 +/- 3 h in groups 1, 2, and 3, respectively. In patients with moderate renal failure, dosage adjustment of rufloxacin is not needed. The rufloxacin dose interval should be prolonged to 48 h as the GFR falls below 30 ml/min/1.73 m2.
Identification of an expanded CAG repeat in the Huntington's disease gene (IT15) in a family reported to have benign hereditary chorea.
Benign hereditary chorea (BHC) is a rare autosomal dominant disorder characterised by the onset of non-progressive chorea in childhood and the absence of cognitive impairment. Using primers flanking the (CAG)n repeat in IT15, expansion of which is associated with HD, we have detected an abnormal PCR product in four affected members from one family where affected subjects were originally reported to have BHC. The expanded allele contains 38 repeats in the affected parent and this undergoes further enlargement to 39 and 45 repeats in the two affected offspring. We conclude that the diagnostic criteria for BHC should include a normal result from analysis for the (CAG)n expansion identified in HD.
Significant linkage disequilibrium between the Huntington's disease locus and markers at loci D4S10, D4S95, and D4S111 in Northern Ireland.
An analysis of the Northern Ireland Huntington's disease (HD) population of 75 families showed significant linkage disequilibrium between the HD gene and DNA markers at D4S95, D4S10, and D4S111. As the linkage disequilibrium at loci D4S10 and D4S111 is different from previous studies in the UK, but similar at locus D4S95, this suggests either that the HD mutation(s) in the Northern Ireland and British populations is not of common origin or that the haplotype of the common HD mutation has changed over time subsequent to divergence from a common origin.
DNA storage and duplicate sampling: lessons learnt from testing for Huntington's disease.
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Age at onset in Huntington's disease and methylation at D4S95.
Age at onset in Huntington's disease (HD) is variable and is influenced by parental sex, paternal age, and genetic background. Several recent models have tried to explain this variable expressivity by invoking parental imprinting and related aspects of epigenetic inheritance. Some of these mechanisms may result in variable DNA methylation at or near the HD gene. We show here that methylation at D4S95, a locus tightly linked to the HD gene, is highly variable. A comparison between patients with early onset HD, late onset HD, and normal controls showed no significant correlation between methylation and age at onset. However, we found a significant association of the age of the patient with demethylation at D4S95. Older persons tend to have lower levels of methylation at this locus. This observation is of interest with regard to studies that show an effect of paternal age, or more generally of 'ageing genes', on age at onset in HD.
Huntington disease in County Donegal: epidemiological trends over four decades.
The prevalence rate of Huntington disease in County Donegal between 1961 and 1991 showed a decrease from 4.4 to 1.6 per 100,000 population. Emigration and reduction in family size probably account for the progressive decline in prevalence. Over the same time period in the rest of Europe, prevalence has declined only gradually, or has remained static.
Cardiovascular abnormalities in the oculo-auriculo-vertebral spectrum (Goldenhar syndrome).
We describe the phenotypic characteristics of 25 individuals with oculo-auriculo-vertebral spectrum (OAVS) and its variants, seen in Northern Ireland between 1969-1989, with special reference to cardiovascular defects. We report the type and prevalence of cardiovascular findings and also estimate the minimum prevalence rate of OAVS to be 1 in 45,000.
Underreporting of pedestrian accidents.
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Interstitial deletion 8p21.3----p23.1 in a 6-year-old girl.
We present a 6-year-old mentally retarded girl. Chromosome analysis showed an interstitial deletion of chromosome 8; 46,XX,del(8) (pter----p23.1::p21.3----qter). The proposita had normal activities of glutathione synthetase reductase (GSR) and factor VII. Parental chromosomes were normal.