The same twins taking part in the mole and MAPS studies at ages 12, 14 and 16 donate a small blood sample at each visit and this is analysed in a Coulter counter to obtain counts of various blood cell types. Lymphocytes are also typed with markers CD3, CD4, CD8, CD19 and CD56. Analysis of data from nearly 400 pairs at age 12 reveals that most of these haematological measures are strongly inherited, at least 80 per cent of variance being genetic. We are studying the longitudinal development of these cell numbers and using sib-pair linkage analysis to find genes of major influence on them.
(D.M. Evans, N.G. Martin, in collaboration with Prof. I. Frazer, The University of Queensland)