Identification of novel variants in hereditary spherocytosis patients by whole-exome sequencing

Defects in erythrocyte membrane proteins can cause the most common type of inherited hemolytic anemia, so called hereditary spherocytosis (HS). It is characterized by the appearance of spherocytes in peripheral blood, hemolytic anemia, splenomegaly, jaundice and gallstones. Due to difficulty of diagnosis solely based on aforementioned parameters, the addition of genetic testing seems to be effective and most acknowledged. Up to date, pathogenic variations in five genes encoding membrane proteins (ANK1, SPTA1, SPTB, SLC4A1, EPB42) are identified to cause HS. Here, we have studied the genetic spectrum in forty-one patients with clinically suspected HS and their families, as well as their genotype-phenotype correlations. Pathogenic mutations in ANK1, SPTB, SLC4A1 and SPTA1 were found in 17 (41.5 %), 12 (29.3 %), 7 (17.1 %) and 5 (12.2 %) patients, respectively. Deleterious variants include 12 missense, 15 nonsense, 12 frameshift, and 4 splicing variants. Among these variations 32 were novel. In our genotype-phenotype analysis, platelet levels in SPTB (p = 0.021) and SLC4A1 (p = 0.02) patients were found to be significantly lower than ANK1 patients. In addition, LDH levels in SPTB patients were remarkably lower than patients with ANK1 mutations (p = 0.025).