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Haemoglobin H disease in California

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Haemoglobin (Hb) H disease is a form of α-thalassaemia prevalent among Asian and Mediterranean people. In its usual (deletional) form, three of the four α-globulin loci are missing and patients have a mixture of HbH and HbA with some HbA2. Asian immigration has led to an increase in the prevalence of HbH disease on the west coast of the USA. Most cases are of deletional HbH disease but symptomatic disease is more commonly of an HbH subtype called haemoglobin H Constant Spring (HCS) disease.A report from Oakland, California (Ashutosh Lal and colleagues. N Eng J Med 2011;364:710–18; see also editorial, ibid: 770–1) has presented data from 86 cases of HbH disease, including 23 of HCS disease. The children were mainly from Asian families (70); four were of Hispanic origin, three African-American and nine of mixed ancestry. The Asian families were mainly from China, the Philippines, Laos, Vietnam and Cambodia. Of the 23 children with HCS disease, 14 were of Laotian family origin, five Chinese and four Cambodian.

The children with deletional HbH disease remained well on the whole and grew normally. HCS disease was more severe with growth impairment from infancy and anaemia that got worse with infections and often needed blood transfusion. Only 3% of HbH cases, but 80% of HCS, needed transfusion by the age of 20 years. Among the HCS group, 13% needed transfusion in infancy and 50% by the age of 6 years. Splenectomy increased Hb concentrations and reduced transfusion requirements.

HCS disease is more severe than deletional HbH disease. In California, it occurs mainly in immigrant families from Laos, China and Cambodia. Families at risk should be offered neonatal screening.

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  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.