Clinical and Molecular Assessment of Iranian Families with Severe Congenital Neutropenia, Identification of HYOU1 and SHOC2 as Potential Novel Gene Defects

Neutropenia congenita grave (SCN) is a rare disease with a genetically and clinically heterogeneous nature, usually diagnosed in childhood, with an elevated risk of infections such as otitis, skin infections, pneumonia, deep abscesses, and septicemia. Patients with SCN also have an increased risk of leukemia, and mutations in the ELANE and the HAX1 genes have been observed in those patients. This study was conducted to genetically screen six Iranian families with SCN who have at least one affected person. In the first step, all exons and intron boundaries of ELANE and HAX1 genes were sequenced in probands. Cases with no pathogenic mutations were tested through whole-exome sequencing (WES). Analysis showed five different variants in ELANE (c.377 C>T), HAX1 (c.130_131 insA), HYOU1 (c.69 G>C and c.2744 G>A) and SHOC2 (c.4 A>G) genes in four families. We found that two out of six families had mutations in ELANE and HAX1 genes. Moreover, we found two novel mutations at the HYOU1 gene that had not previously been reported, as well as a pathogenic mutation at SHOC2 with multiple phenotypes, that will contribute to determining the genetic basis for SCN. Our study revealed that WES could help diagnose SCN, improve the classification of neutropenia, and rule out other immunodeficiencies such as autoimmune neutropenia, primary immunodeficiency diseases, and inherited bone marrow failure syndromes.