Q: My wife and I are from Indian and staying in Sydney. My wife has been diagnosed positive for thalassaemia. She is 18 weeks pregnant with our first baby. She has low levels of iron in the body. I have also undergone blood tests and there is no confirmatory evidence of thalassaemia in my blood, though even I have low iron levels. As per the Australian law, we need to go for genetic counselling to discuss about the chances of having a thalassaemic baby. What complications can arise in the baby? Is there any thing to worry about? At the moment, my wife and I are taking iron supplements daily. Please advise.

A:Thalassaemias are a group of genetic diseases caused by the production of abnormal haemoglobin, the red coloured protein present in red blood cells that transports oxygen in the body. Haemoglobin comprises two beta (b)-globin and two alpha (a)-globin chains, their production being governed by 2b and 4a genes respectively. In b-thalassaemia, the production of b-chain is abnormal while in a-thal it is the a-chain. When only one beta-globin gene is affected (thal minor or trait or carrier), it results in mild anaemia not requiring treatment but the involvement of both genes results in severe disease (thalassaemia major or intermedia) requiring regular treatment and follow-up from infancy. The beta-thalassaemia syndromes (thalassaemia major and b-thalassaemia intermedia) occur due to the absence of or a reduction in the synthesis of structurally normal beta-globin chains the normal constituents of haemoglobin. This beta-globin chain deficiency leads to severe anaemia by impairing the formation of functional Hb A (the normal Hb found in adults). The severity of these disorders is determined primarily by the type of the gene defect as well as the gene dosage. I think you mean your wife is a b-thal carrier while you are normal. The normal Hb A2 level in an adult is less than 3.5% and it is elevated (>4%) in b-thalassaemia trait. Beta thalassaemia trait is a clinically benign disorder. The importance lies in the fact that if both parents are carriers (i.e. carry one abnormal b-gene), an offspring may co-inherit a b-thalassaemia gene from both the parents making it homozygous resulting in a medically significant thalassaemia (b-thalassaemia major). As you are normal (and I assume your complete blood count is normal), there is no problem. There are, however, very rare instances where a thal carrier may have normal Hb A2 level and such cases can be detected only by DNA analysis (so called Silent or near silent b-thalassaemia trait). You need not take iron supplements if you are not iron deficient.