Exome sequencing results in successful diagnosis and treatment of a severe congenital anemia

Whole-exome sequencing is increasingly used for diagnosis and identification of appropriate therapies in patients. Here, we present the case of a 3-yr-old male with a lifelong and severe transfusion-dependent anemia of unclear etiology, despite an extensive clinical workup. Given the difficulty of making the diagnosis and the potential side effects from performing interventions in patients with a congenital anemia of unknown etiology, we opted to perform whole-exome sequencing on the patient and his parents. This resulted in the identification of homozygous loss-of-function mutations in the EPB41 gene, encoding erythrocyte protein band 4.1, which therefore causes a rare and severe form of hereditary elliptocytosis in the patient. Based on prior clinical experience in similar patients, a surgical splenectomy was performed that resulted in subsequent transfusion independence in the patient. This case illustrates how whole-exome sequencing can lead to accurate diagnoses (and exclusion of diagnoses where interventions, such as splenectomy, would be contraindicated), thereby resulting in appropriate and successful therapeutic intervention—a major goal of precision medicine.