Editorial: Genetics and population health

There has been a widespread belief that genetic disorders are of little importance in low income countries, an opinion that is perhaps understandable given the often daunting prevalence of infectious diseases and nutritional problems faced by these populations. The failure to recognize genetic disorders as significant contributors to the overall disease profile of low income countries is, however, a serious error. For example, an estimated 7.6 million children are born per year with a severe congenital or genetic disorder (Alwan and Modell 2003), and one in seven of the world’s population are carriers of a haemoglobin disorder (WHO 2002). In both cases a large majority of those affected are resident in low income countries, which currently comprise over 80% of the global population (PRB 2004). There is also convincing preliminary evidence that some sub-populations are genetically predisposed to contract serious infectious diseases, including tuberculosis and leprosy (Pitchappan 2002). Further, because of the requirement to treat β-thalassaemia major individuals with regular blood transfusions, in 2003 Thalassaemia International Federation estimated that 30–80% of all cases worldwide were infected with hepatitis B and/or hepatitis C, a testament to the lack of adequate blood screening facilities in low income countries. Thus the contribution of genetic disorders to global population disease profiles, directly and indirectly, is of major significance

A community profile of alpha-thalassaemia in Western Australia

Objective: To investigate the current prevalence of ;1-thalassaemia in the population of Western Australia, which has received substantial immigration from South-East Asia during the last 30 years. Method: Over a 1-year period commencing July 2002, ;1-thalassaemia DNA testing was performed on 920 blood samples received from the Migrant Health Service, referring doctors or pathology laboratories in Western Australia. Molecular testing for ;1-thalassaemia was performed on extracted DNA for single and double ;1-globin gene deletions and mutations by PCR. Results: An ;1-globin gene abnormality was detected in 35.4% (326/920) of samples. There were 177 cases (50.6%) with a single gene deletion ;1+-thalassaemia, most commonly 133.7 kb, and 102 cases (31.2%) with double ;1-gene deletions (;10-thalassaemia), including 7 cases of HbH disease. Conclusion: Overall, the findings amount to 1.7 new cases of ;1-thalassaemia per 10,000 population in the 12-month period and demonstrate that ;1-thalassaemia is an increasingly common disorder in the Western Australian population. This has important implications for community outreach programmes, genetic counselling and the screening of at-risk populations

A community profile of a-thalassaemia in Western Australia

Over the last 50 years there has been substantial migration to Australia. Initially migrants came from Europe, but over the last 30 years significant numbers have originated in SouthEast Asia and more recently SubSaharan Africa. Because of the changed migration pattern it is believed that a-thalassaemia mutations have been introduced. This paper reports the results of a one-year study of the prevalence of a-thalassaemia in Western Australia. Testing for a-thalassaemia was performed on 920 blood samples referred from doctors or pathology laboratories in Western Australia as part of the investigation for a haemoglobinopathy. Molecular testing was performed on extracted DNA for single and double a-globin gene deletions and mutations by PCR. An a-globin gene abnormality was detected in 35.4% (326/920) of samples. There were 177 cases (50.6%) with a single gene deletion a+-thalassaemia, most commonly -a3.7kb, and 102 cases (31.2%) with double a-gene deletions (a0- thalassaemia), most commonly --SEA, including 7 cases of HbH disease compound heterozygotes, were also detected. These findings amount to 1.7 new cases of a-thalassaemia per 10,000 population in the 12-month period and demonstrate that a-thalassaemia is an increasingly common disorder in the Western Australian population. This has implications for genetic counselling and health screening of at-risk populations

Y-chromosome and mtDNA studies into the population structure of the Christmas Island community

Christmas Island is a remote Australian territory located close to the main Indonesian island of Java, and 1,540 km from the coast of Western Australia. The Island was annexed by Great Britain in 1888 and indentured Chinese labourers were recruited to mine the phosphate deposits. After WWII additional labourers were hired from Malaysia. The present population comprises approximately 60% Chinese, 25% Malay and 15% European or other. To determine the genetic structure of the Christmas Island population, markers on the Y-chromosome and mitochondrial DNA (mtDNA) were investigated in 92 individuals. Y-chromosome biallelic polymorphisms revealed moderate to high frequencies of markers M95 (15%), M119 (23.3%) and M122 (36.7%), consistent with ancient male origins in Southern China and SE Asia. mtDNA hypervariable segment I (HVS-I) sequences revealed high levels of genetic similarity to the Southern Chinese, Hong Kong Cantonese, Indonesian Moluccas and Thai. The mtDNA COII/tRNALys 9-bp deletion was present at a relatively high frequency (31.5%), and in conjunction with the HVS-I polymorphisms suggested two distinct origins from China and SE Asia. The present study provides a useful model for the investigation of contemporary populations derived from different origins and could play an important role in the study of inherited disease

Single-tube multiplex-PCR screen for anti-3.7 and anti-4.2 α-globin gene triplications

10.1373/49.10.1679Clinical Chemistry49101679-1682CLCH