In order to ascertain whether young familial hypercholesterolemic subjects without atherosclerotic lesions demonstrable on a carotid echo‐Doppler show decreased erythrocyte deformability, we determined the erythrocyte elongation index (EEI) by means of a shear stress diffractometer (Rheodyn SSD) in twenty‐four children with heterozygous familial hypercholesterolemia (FH), aged
12\pm 3
years, and their corresponding affected parent. The parents were twenty‐three adults with heterozygous FH aged,
32\pm 6
years. The control group was made up of a similar number of well matched healthy volunteers. The EEI at 6, 12, 30 and 60 Pa showed no statistical differences between FH children and their control group, or between FH parents and their control group. No correlations were found between EEI and plasma lipids or lipoproteins at any of the shear stresses used. These results suggest that the red blood cells of young familial hypercholesterolemic subjects who show no deterioration of the vascular tree are not less deformable than those of healthy normolipemic subjects, and that dyslipemia itself does not produce alterations that damage the rheological properties of the red blood cell.
