Search PubMed⌕ Search

Biomedical subjects

J M Old

Publications and source records attributed to J M Old.

At least 19 recordsLinked to original sources
PubMed2000

Thalassaemia in Sri Lanka: implications for the future health burden of Asian populations. Sri Lanka Thalassaemia Study Group.

BACKGROUND: Thalassaemias pose an increasing problem for the Indian subcontinent and many Asian countries. We analysed the different types of thalassaemia in the Sri Lankan population, surveyed gene frequencies in schoolchildren, and estimated the burden of disease and requirements for its control. METHODS: We analysed blood samples from patients attending clinics in nine hospitals and defined the different types of beta thalassaemia by high-performance liquid chromatography (HPLC) and DNA analysis. The range of mutations was obtained by analysis of beta-globin genes. Capillary blood was obtained from schoolchildren from different parts of the island and analysed by HPLC to provide an approximate assessment of the carrier frequency of beta thalassaemia and haemoglobin E (HbE). To estimate the frequency of alpha thalassaemia the alpha-globin genotypes were also analysed when it was possible. FINDINGS: Blood samples were obtained from 703 patients with beta thalassaemia and from 1600 schoolchildren. The thalassaemia mutations were unevenly spread. Although 23 different beta-thalassaemia mutations were found, three accounted for the thalassaemia phenotype in about 70% of the patients, most whom are homozygotes or compound heterozygotes for IVS1-5 (G-->C) or IVS1-1 (G-->A). The third common mutation, codon 26 (G-->A), which produces HbE, interacts with one or other of these mutations to produce HbE/beta thalassaemia; this comprises 13.0-30.9% of cases in the main centres. Samples from 472 patients were analysed to determine the alpha-globin genotype. Overall, 15.5% patients were carriers for deletion forms of alpha+ thalassaemia. Average gene frequencies showed that there will be more than 2000 patients requiring treatment at any one time, in the future, of whom those with HbE/beta thalassaemia will account for about 40%. INTERPRETATION: In Sri Lanka, interactions of the two common beta-thalassaemia alleles will nearly always result in a transfusion-dependent disorder. However, about 40% of patients will have HbE/beta thalassaemia, which has a variable course. The management of these disorders could require about 5% of the total health budget. We need to learn more about the natural history and appropriate management of HbE/beta thalassaemia if resources are to be used effectively.

Adult↗
PubMed2000

Development of the immune system and immunological protection in marsupial pouch young.

At birth the tissues of marsupial immune system are underdeveloped. The young animal is not immunocompetent. Histological and immunohistochemical studies of pouch young epithelial tissues provide a clear picture of tissue development but the timing of onset of immunocompetence awaits definition. The survival of the neonatal marsupial in a microbially rich environment is dependent on maternal strategies, including immunoglobulin transfer via milk and, in some species, prenatally via the yolk sac placenta. It is also likely that pouch secretions play a role. This review summarizes our current knowledge of the pathway of immunological development in marsupials and the protection and threats afforded by the pouch environment.

Animals↗
PubMed2000

Rapid detection of alpha-thalassaemia deletions and alpha-globin gene triplication by multiplex polymerase chain reactions.

We describe a sensitive, reliable and reproducible method, based on three multiplex PCR assays, for the rapid detection of seven common alpha-thalassaemia deletions and one alpha-globin gene triplication. The new assay detects the alpha0 deletions - -SEA, - (alpha)20.5, - -MED, - -FIL and - -THAI in the first multiplex PCR, the second multiplex detects the -alpha3.7 deletion and alphaalphaalphaanti3.7 variant, the third multiplex detects the -alpha4.2 deletion. This simple multiplex method should greatly facilitate the genetic screening and molecular diagnosis of these determinants in populations where alpha-thalassaemias are prevalent.

Gene Deletion↗
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↗