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Intra-familial aggregation and heritability of aortic versus brachial pulse pressure after imputing pretreatment values in a community of African ancestry

Redelinghuys, Michelle; Norton, Gavin R.; Maseko, Muzi J.; Majane, Olebogeng H.I.; Woodiwiss, Angela J.

doi: 10.1097/HJH.0b013e328352aeaa
ORIGINAL PAPERS: Genetic aspects

Aim: To compare the intra-familial aggregation and heritability of central (aortic) (PPc) versus peripheral (brachial) (PPp) pulse pressure after imputing pretreatment blood pressures (BPs) in treated participants in a community of black African ancestry.

Methods: Central PPc [generalized transfer function (GTF) and radial P2-derived] was determined with applanation tonometry at the radial artery (SphygmoCor software) in 946 participants from 258 families with 23 families including three generations from an urban developing community of black Africans. In the 24.1% of participants receiving antihypertensive treatment, pretreatment brachial BP was imputed from published overall averaged effects of therapy grouped by class and dose, specific for groups of black African descent. From these data PPc was estimated from proportionate differences in central aortic and brachial PP. Heritability estimates were determined from SAGE software. Echocardiography was evaluated in 507 participants in order to determine stroke volume.

Results: With adjustments for confounders, parent–child (P < 0.05) and sibling–sibling (P < 0.0005) correlations were noted for log PPc, whilst for log PPp only sibling–sibling correlations were noted. No mother–father correlations were noted for either PPc or PPp. Independent of confounders the heritability for log GTF-derived (h 2 = 0.33 ± 0.07, P < 0.0001) and P2-derived (h 2 = 0.30 ± 0.07, P < 0.0001) PPc was greater than the heritability for log PPp (h 2 = 0.11 ± 0.06, P < 0.05) (P < 0.05 for comparison of heritability estimates).

Conclusion: After imputing pretreatment BP values, central aortic PP is significantly more inherited than brachial PP. These data suggest that in groups of African descent the genetic determinants of PP may be underestimated when employing brachial rather than central aortic PP measurements.

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Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

Correspondence to Angela J. Woodiwiss, Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, University of the Witwatersrand Medical School, 7 York Road, Parktown, 2193 Johannesburg, South Africa. Tel: +27 11 717 2363; fax: +27 11 717 2153; e-mail: angela.woodiwiss@wits.ac.za

Abbreviations: ASSOC, Marker-Trait Associations in Pedigree Data; BMI, body mass index; BP, blood pressure; DBP, diastolic blood pressure; GTF, generalized transfer function; HbA1c, glycated haemoglobin; MAP, mean arterial pressure; P2, peak pressure at the second pressure wave of the radial pulse; PP, pulse pressure; PPc, central (aortic) pulse pressure; PPp, peripheral (brachial) pulse pressure; SAGE, Statistical Analysis for Genetic Epidemiology; SBP, systolic blood pressure; SBPc, central (aortic) systolic blood pressure

Received 29 March, 2011

Revised 9 December, 2011

Accepted 16 February, 2012

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© 2012 Lippincott Williams & Wilkins, Inc.