Sickle Cell Trait and Splenic Syndrome

The peculiar susceptibility of nonblack carriers of the sickle cell trait to splenic infarction or sequestration on ascent to moderately high altitudes seems to be real, although ascertainment bias cannot totally be excluded.

Abstract

To the Editor.— The peculiar susceptibility of nonblack carriers of the sickle cell trait to splenic infarction or sequestration on ascent to moderately high altitudes seems to be real, although ascertainment bias cannot totally be excluded. Why should this be so? The recent report by Lane and Githens 1 might provide a clue. The mean corpuscular volume (MCV) of their patients—94.5 femtoliters (fL)— seems to be considerably higher than the MCV of black patients with sickle trait having hemoglobin S concentrations of about 40%. For example, in 90 black men with hemoglobin S levels between 35% and 40%, the MCV was 83.2 fL, and in 116 black men with hemoglobin S levels greater than 40%, the MCV was 86.9 fL (A. Kennedy, MD, D. A. Walsh, PhD, R. Nicholson, MS, et al, unpublished data, 1985). α-Thalassemia is the major modulator of hemoglobin S levels and MCV in blacks with sickle