a1 Queensland Institute of Medical Research and Joint Genetics Program, University of Queensland, Brisbane. nickM@qimr.edu.au
a2 Centre for Immunology and Cancer Research, University of Queensland, Princess Alexandra Hospital, Brisbane, Australia.
a3 Queensland Institute of Medical Research and Joint Genetics Program, University of Queensland, Brisbane.
The genetic and environmental determinants of variation in blood cell size and number were investigated in 392 pairs of 12-year-old twins. The following blood cell indices were measured: haemoglobin, red blood cell count, haematocrit, mean corpuscular volume, platelet number, total white cell count, level of neutrophils, monocytes, eosinophils, total lymphocytes, CD3+ lymphocytes, CD4+ lymphocytes, CD8+ lymphocytes, CD19+ lymphocytes, CD56+ lymphocytes and CD4+ /CD8+ ratio. Genetic factors contributed significantly to all blood cell measures accounting for between 61 and 96% of variance. Heritability estimates did not differ significantly between males and females, although the sample size of the present study was not large enough to exclude the possibility of sex-limited gene expression. Common environmental factors were important in determining red blood cell count and haematocrit, but were not important in determining basal levels of any white blood cell type.
(Received July 19 1999)
(Accepted September 17 1999)
c1 Correspondence: Professor NG Martin, Queensland Institute of Medical Research, PO Royal Brisbane Hospital, Brisbane 4029, Australia. Tel: + 61 7 3362 0278; Fax: + 61 7 3362 0101;