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Haptoglobin, alpha‐thalassaemia and glucose‐6‐phosphate dehydrogenase polymorphisms and risk of abnormal transcranial Doppler among patients with sickle cell anaemia in Tanzania
Author(s) -
Cox Sharon E.,
Makani Julie,
Soka Deogratias,
L'Esperence Veline S.,
Kija Edward,
DominguezSalas Paula,
Newton Charles R. J.,
Birch Anthony A.,
Prentice Andrew M.,
Kirkham Fenella J.
Publication year - 2014
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/bjh.12791
Subject(s) - haptoglobin , medicine , hemoglobinopathy , tanzania , transcranial doppler , hemolytic anemia , endocrinology , environmental science , environmental planning
Summary Transcranial D oppler ultrasonography measures cerebral blood flow velocity ( CBF v ) of basal intracranial vessels and is used clinically to detect stroke risk in children with sickle cell anaemia ( SCA ). Co‐inheritance in SCA of alpha‐thalassaemia and glucose‐6‐phosphate dehydrogenase ( G 6 PD ) polymorphisms is reported to associate with high CBF v and/or risk of stroke. The effect of a common functional polymorphism of haptoglobin ( HP ) is unknown. We investigated the effect of co‐inheritance of these polymorphisms on CBF v in 601 stroke‐free T anzanian SCA patients aged <24 years. Homozygosity for alpha‐thalassaemia 3·7 deletion was significantly associated with reduced mean CBF v compared to wild‐type (β‐coefficient −16·1 cm/s, P = 0·002) adjusted for age and survey year. Inheritance of 1 or 2 alpha‐thalassaemia deletions was associated with decreased risk of abnormally high CBF v, compared to published data from Kenyan healthy control children (Relative risk ratio [ RRR ] = 0·53 [95% confidence interval ( CI ):0·35–0·8] & RRR = 0·43 [95% CI :0·23–0·78]), and reduced risk of abnormally low CBF v for 1 deletion only ( RRR = 0·38 [95% CI :0·17–0·83]). No effects were observed for G6 PD or HP polymorphisms. This is the first report of the effects of co‐inheritance of common polymorphisms, including the HP polymorphism, on CBF v in SCA patients resident in Africa and confirms the importance of alpha‐thalassaemia in reducing risk of abnormal CBF v.