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Biomedical subjects

J M Old

Publications and source records attributed to J M Old.

At least 37 records · Page 2Linked to original sources
PubMed1999

Multicentric origin of hemochromatosis gene (HFE) mutations.

Genetic hemochromatosis (GH) is believed to be a disease restricted to those of European ancestry. In northwestern Europe, >80% of GH patients are homozygous for one mutation, the substitution of tyrosine for cysteine at position 282 (C282Y) in the unprocessed protein. In a proportion of GH patients, two mutations are present, C282Y and H63D. The clinical significance of this second mutation is such that it appears to predispose 1%-2% of compound heterozygotes to expression of the disease. The distribution of the two mutations differ, C282Y being limited to those of northwestern European ancestry and H63D being found at allele frequencies>5%, in Europe, in countries bordering the Mediterranean, in the Middle East, and in the Indian subcontinent. The C282Y mutation occurs on a haplotype that extends </=6 Mb, suggesting that this mutation has arisen during the past 2,000 years. The H63D mutation is older and does not occur on such a large extended haplotype, the haplotype in this case extending </=700 kb. Here we report the finding of the H63D and C282Y mutations on new haplotypes. In Sri Lanka we have found H63D on three new haplotypes and have found C282Y on one new haplotype, demonstrating that these mutations have arisen independently on this island. These results suggest that the HFE gene has been the subject of selection pressure. These selection pressures could be due to infectious diseases, environmental conditions, or other genetic disorders such as anemia.

Alleles↗
PubMed1999

The association of Hb Khartoum [beta124(H2)Pro-->Arg] with gamma+-thalassemia is responsible for hemolytic disease in the newborn of a Sudanese family.

The unstable Hb Khartoum with a Pro-->Arg replacement at position beta124 was identified by isoelectrofocusing, high performance liquid chromatography, and peptide mapping in a mother and two male children of a Sudanese family. All three were heterozygous for the abnormal hemoglobin; the father and a third male child did not carry the mutation. The mother was also homozygous for two putative gamma+-thalassemia point mutations, one affecting both Agamma and Ggamma genes at IVS-II-115 (A-->G), and one affecting the Ggamma gene at the 3' untranslated region (-A) at position -6 from the polyadenylation site. The father had normal gamma genes. All three children were heterozygous for both the gamma+-thalassemia mutations. The two older children, who were compound heterozygotes for Hb Khartoum/gamma+-thalassemia, presented at birth with severe neonatal jaundice which necessitated exchange blood transfusions. Other causes of neonatal jaundice were excluded. The third male child, who did not carry the Hb Khartoum anomaly but was heterozygous for gamma+-thalassemia, did not develop neonatal jaundice. It is concluded that the instability of Hb Khartoum in combination with gamma+-thalassemia is responsible for neonatal hemolytic anemia in this family.

Adult↗
PubMed1998

The effect of oestrus and the presence of pouch young on aerobic bacteria isolated from the pouch of the tammar wallaby, Macropus eugenii.

Qualitative changes in the culturable, aerobic bacterial flora isolated from the tammar pouch have been documented over the period leading up to oestrus, at the time of anticipated birth and in absence and presence of pouch young of varying ages. In a group of 12 animals studied thirty species of aerobic bacteria were isolated. Twenty five species were found in pouches with no pouch young, 9 in pouches with young less than 3 weeks of age and 9 in pouches containing older animals. Gram positive organisms including Corynebacterium spp., Micrococcus spp. and Staphylococcus spp. were the most frequent isolates, regardless of reproductive status. Whilst Gram-negative rods Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterobacter aerogenes, and Escherichia coli were found in pouches with and without pouch young, but not in pouches close to oestrus, at the time of birth or in the presence of very young animals (< 6 days). While pouches without pouch young displayed the greatest diversity of bacterial species, there were still significant numbers of bacterial species in those containing pouch young. Results suggest that the microbial population of the tammar pouch does not seriously compromise the well-being of the young animal during crucial stages of immunological development. The data are consistent with observations on the microflora of the quokka pouch but not with data from the koala.

Animals↗
PubMed1998

Prevalence and molecular basis of alpha thalassaemia in British South Asians.

OBJECTIVES: To determine the prevalence and molecular basis of alpha thalassaemia in the British South Asian population, and the implications for genetic screening for haemoglobin disorders. METHODS: 397 South Asian Subjects were screened for haemoglobinopathy with measurement of bull blood count, haemoglobin electrophoresis, haemoglobin A2 quantification, and plasma ferritin determination. alpha Globin gene mapping was successfully performed on 266 stored buffy coat samples using a Southern blot technique after hybridisation with Bg/II and BamHI. RESULTS: Of the 266 subjects in whom gene mapping was performed, 28 had a single alpha+ thalassaemia deletion and one was homozygous for this deletion (gene frequency 0.056). Half of the heterozygotes had normal mean cell haemoglobin (MCH) values. A further 16 subjects had probable non-deletional alpha+ thalassaemia. None had alpha 0 thalassaemia. CONCLUSIONS: alpha Thalassaemia is by far the commonest haemoglobinopathy in British South Asian subjects, but is not a cause of serious genetic risk. Screening and counselling should focus on subjects with more marked red cell hypochromia (MCH < 25 pg), thus concentrating resources on subjects of different ethnic origins who may carry the alpha 0 thalassaemia gene.

Adolescent↗
PubMed1997

Relationship between the severity of beta-thalassaemia syndromes and the number of alleviating mutations.

Thalassaemia intermedia, defined as homozygous beta-thalassaemia in which patients are not transfusion-dependent, covers a wide range of clinical severity. It may arise because one or more genetic factors ameliorate the otherwise severe phenotype of thalassaemia major. Exactly which and how many such mutations are necessary to produce a thalassaemia intermedia phenotype is incompletely understood, although such information would be useful both clinically and for prenatal diagnosis. We examined DNA from 28 patients with thalassaemia intermedia resident in London and 28 matched patients with thalassaemia major, for 3 types of genetic modifying factors, namely; mild beta-thalassaemia mutations, the upstream XmnI G-gamma globin gene polymorphism, and alpha-globin gene deletions. The results show that the number of alleviating mutations present has a large influence on the phenotype of patients with homozygous beta-thalassaemias. A single alleviating mutation was present in 56% of thalassaemia intermedia subjects compared with 26% of thalassaemia major subjects. Two alleviating mutations were present in 33% of thalassaemia intermedia subjects compared with 1 thalassaemia major subject. No patients with thalassaemia major had 3 alleviating mutations, in contrast to 11% of those with thalassaemia intermedia. Although the findings did not account for the full range of phenotypic variation, such information is of potential value both in the clinical management and the prenatal diagnosis of homozygous beta-thalassaemia.

Adolescent↗
PubMed1996

Haplotype analysis of the Mexican frameshift Cd 11 (-T) and -28 A->C beta-thalassemia alleles.

The origins of the -28 A->C and frameshift Cd 11 - T(Fs CD 11-T)alleles were investigated by beta-globin cluster haplotype analysis. These alleles were found in a Mexican mestizo family with beta-thalassemia (beta-thal). The -28 A->C mutation was described previously in Kurdish Jews linked to the most common haplotype in the world(+----++),the same haplotype observed in this Mexican family. Therefore, it is not possible to assess a new origin of the -28 A->C mutation in our population. The Fs Cd 11 -T allele, not reported to date in any other populations, was linked to the -++--+-haplotype (sixth in frequency in the world). This haplotype has not been reported in association with any beta-thal mutant, suggesting a Mexican origin for the Cd 11 -T mutation.

Adolescent↗
PubMed1995

Detection of beta-thalassaemia mutations using DNA heteroduplex generator molecules.

In this report we describe a rapid polymerase chain reaction (PCR) based method for the detection of beta-thalassaemia (beta-thal) mutations. This method is based on the visualization of unique DNA heteroduplex banding patterns, following non-denaturing polyacrylamide gel electrophoresis, resulting from hybridization between mutant PCR products and synthetic DNA heteroduplex generator molecules. Using the Singaporean population, which consists of Chinese, Malay and Asian Indian ethnic groups, as a model, we have constructed and evaluated three DNA heteroduplex generator molecules for the detection of the common beta-thalassaemia mutations found in this population. The results show that these three molecules are capable of detecting approximately 95% of the mutations found in the Singaporean population. We propose that this technology may be applied as an alternative screening strategy for beta-thalassaemia mutations because it is technically simple, flexible, cost-effective, and requires only minimal laboratory resources.

Base Sequence↗
PubMed1994

The spectrum of beta thalassaemia mutations in the UAE national population.

The beta thalassaemia alleles in 50 beta thalassaemia heterozygotes originating from many parts of the United Arab Emirates (UAE) have been characterised using the allele specific priming technique of the polymerase chain reaction (PCR). The IVSI-5 (G-->C) mutation was found to be present in 66%, while six other alleles occurred at the much lower frequencies of 2% to 8%. These were codon 8/9 (+G), IVSI-1, 3' end (-25 bp), codon 5 (-CT), IVSII-1 (G-->A), codon 30 (G-->C), and codon 15 (G-->A). The mutation types and percentages are compared with other Mediterranean Arab countries and neighbouring areas. It is proposed that IVSI-5 and other Asian Indian mutations were introduced into the UAE by population migration from the region previously known as Baluchistan. These findings should be useful for genetic counselling and the development of a first trimester prenatal diagnosis programme based on direct detection of mutations in the UAE.

Base Sequence↗
PubMed1994

Detection of beta-thalassaemia mutations in eastern Indian population by polymerase chain reaction.

We report here the application of a non-radioactive amplification refractory mutation system (ARMS) for the direct detection of beta-thalassaemia using polymerase chain reaction. Seven beta-thalassaemia mutations accounting for 89 per cent (71 of 80) of the alleles in eastern Indian population have been identified and majority (67.5%) were due to IVS-1 nt 5 (G-C) mutation. Interestingly, 9 cases did not reveal any of the 17 common mutations reported so far from Indian population.

Alleles↗
PubMed1992

Analysis of beta-globin gene haplotypes in Asian Indians: origin and spread of beta-thalassaemia on the Indian subcontinent.

beta-globin gene haplotypes were determined for 196 normal (beta-A) and 419 thalassaemia (beta-Th) chromosomes of individuals from four different regions of the Indian subcontinent; North-west Pakistan, Gujarat, Punjab and Sindh. Analysis of beta-A and beta-Th haplotypes and haplotype-mutation associations in each regional group along with a consideration of Indian history provided information about the origin and spread of beta-thalassaemia mutations on the Indian subcontinent. The data are consistent with relatively recent and local origins for most beta-thalassaemia mutations. The frequencies of particular alleles differ markedly in various regions and these may be useful population markers. Of the high frequency alleles, intervening sequence 1 (IVS-1) nucleotide 5 (G-C) and codons 41/42 (-CTTT) appear to be older as suggested by multiple haplotype associations and a widespread geographical distribution. The microepidemiology of beta-thalassaemia in this region reflects considerable ethnic diversity, gene flow from population migration and natural selection by malaria infection.

Base Sequence↗
PubMed1992

The beta-thalassaemia mutations in the population of Cyprus.

We have identified the beta-thalassaemia alleles in nearly all known Turkish Cypriot beta-thalassaemia homozygotes and in over 700 Greek Cypriot beta-thalassaemia heterozygotes living on the island of Cyprus. The data confirmed earlier observations that the IVS-I-100 (G-->A) mutation is present for about 74-80%, while three other alleles [IVS-II-745 (C-->G), IVS-I-6 (T-->C), IVS-I-1 (G-->A)] occur at frequencies of 5-8%. Nearly identical percentages were observed for the two Cypriot groups, quite different from those for beta-thalassaemia patients from Greece and Turkey. This suggests close contacts between the two Cypriot communities during many centuries without a major recent influence from Greek or Turkish beta-thalassaemia carriers.

Alleles↗
PubMed1992

beta-Thalassaemia mutations and their linkage to beta-haplotypes in Tamil Nadu in southern India.

A study for screening of beta-thalassaemia mutations by the Amplification Refractory Mutation System (ARMS) and haplotyping by Polymerase Chain Reaction (PCR) was undertaken because there was a paucity of data in Tamil Nadu in Southern India and to initiate a comprehensive prenatal diagnosis programme. A total of 294 alleles were analysed to study the nature of the mutations, of which 146 were beta-thalassaemia alleles. Only four types of beta-thalassaemia mutations were recorded. Of these, 128 alleles were of the variant IVS-1 nt 5 (G-->C). Thirteen had the mutation codon 41/42 (del TCTT), four had the mutation codon 8/9 (insert G) and one had the 619 bp deletion at the 3' end of the gene. The most common mutation, IVS-1 nt 5 (G-->C), was strongly associated with a single haplotype although the association was not absolute. The population of Tamil Nadu in Southern India seems to be ideal for initiating a prenatal diagnosis programme based on direct detection of mutation by ARMS coupled with RFLP linkage analysis.

Alleles↗
PubMed1991

An approach to preimplantation diagnosis of beta-thalassaemia.

Using the polymerase chain reaction (PCR), it was possible to amplify a single copy fragment of the beta-globin gene from 2-32 human embryonic cells obtained from arrested preimplantation embryos. For the detection of beta-thalassaemia mutations, allele specific priming of the PCR using nested primers was employed using approximately 10 pg of DNA from individuals known to carry these mutations. This approach was successful in detecting the presence or absence of five Asian Indian beta-thalassaemia mutations that were selected for this study. In spite of meticulous precautions against contamination, false-positive amplification was observed, a problem that will have to be overcome before this approach can be used in clinical practice.

Base Sequence↗
PubMed1991

The spectrum of beta-thalassaemia mutations on the Indian subcontinent: the basis for prenatal diagnosis.

The beta-thalassaemia mutations in 702 unrelated carriers originating from seven different regions of the Indian subcontinent have been characterized using allele specific priming of the polymerase chain reaction (PCR). It was possible to identify the mutations in 688 (98%) of the individuals studied. Eleven different mutations were identified, of which five common ones accounted for 93.6%; namely the ones at IVS-1 position 5 (G-C), codons 8/9 (+G), IVS-1 position 1 (G-T), codons 41/42 (-CTTT) and the 619 bp deletion at the 3' end of the gene. The mutations at IVS-2 position 1 (G-A) and codon 30 (G-C), previously undescribed in Asian Indians, were found in two and six individuals respectively. Some regional variation in the distribution of beta-thalassaemia alleles was noted. These findings should prove useful for the development of a first trimester prenatal diagnosis programme based on direct detection of mutations.

Alleles↗
PubMed1991

Rare beta-thalassaemia mutations in Asian indians.

Five beta-thalassaemia mutations hitherto undescribed in Asian Indians were identified in beta-thalassaemia carriers originating from the Indian subcontinent by direct sequencing of their beta-globin genes which were amplified by the polymerase chain reaction (PCR). A T-G substitution at IVS 2 position 837, which probably creates an alternative acceptor splice site and a T insertion in codon 88, resulting in a shift in the reading frame with a premature stop codon, are new beta-thalassaemia mutations. The others were framshift codon 5 (-CT), IVS 1 position 110 (G-A) and IVS-1 minus 1 (G-A) which have been described previously in other populations. These results complete the characterization of the beta-thalassaemia mutations in 708 carriers of Asian Indian origin and will enable a comprehensive programme of carrier screening and prenatal diagnosis of beta-thalassaemia in this population.

Alleles↗
PubMed1990

Rapid detection and prenatal diagnosis of beta-thalassaemia: studies in Indian and Cypriot populations in the UK.

The application of the amplification refractory mutation system (ARMS) to the detection of individual beta-thalassaemia mutations in heterozygous parents and "at risk" fetuses has been assessed in Indian and Cypriot immigrant populations in the UK. 100 first trimester prenatal diagnoses have been done, entailing the detection of 17 different mutations. The method, which allows the determination of the mutations in both parental and fetal DNA on the same day, should have wide application to the carrier detection and prenatal diagnosis of monogenic diseases with heterogeneous molecular defects.

Cyprus↗
PubMed1990

Molecular basis for dominantly inherited inclusion body beta-thalassemia.

Analysis of the molecular basis of dominantly inherited beta-thalassemia in four families has revealed different mutations involving exon 3 of the beta-globin gene. It is suggested that the phenotypic difference between this condition and the more common recessive forms of beta-thalassemia lies mainly in the length and stability of the abnormal translation products that are synthesized and, in particular, whether they are capable of binding heme and producing aggregations that are relatively resistant to proteolytic degradation.

Amino Acid Sequence↗