We read with interest the recent perspective article by Klein. 1 Genetic analysis in individuals with severe congenital neutropenia (SCN) indicates that 60% of cases were attributable to heterozygous mutation in ELA2 gene encoding neutrophil elastase. 2 Homozygous mutation in HAX1 gene has been identified in patients with autosomal recessive form of SCN (Kostmann syndrome). 3 Patients with ELA2 or HAX1 mutations reveal a similar morphological and similar clinical phenotype suggesting that there may be common downstream molecular events caused by both mutations.

Interestingly, 28 out of 39 (72%) patients with HAX1 mutations reported were in SCN kindred of Middle eastern descent indicative of consanguinity or intermarrying within specific population groups. 3-5 Five Japanese SCN patients are described6 and only a few cases of true European descent have been documented so far. 3, 5, 7 In the present study we describe the first 2 Italian SCN patients carrying two novel HAX1 mutations associated to neurodevelopment abnormalities. Genomic DNA was extracted from peripheral blood of the patients and the components of their families. Sequencing analysis of HAX1 was performed as previously reported, 3 after excluding mutations in ELA2 gene. 8 In the first kindred the patient, a 4-year old boy, started presenting infections at the age of nine days. After persistent neutropenia and recurrent infections at seven months of life a Kostmann syndrome was diagnosed on the basis of neutrophil count (0.1 χ109/L) and on bone marrow analysis showing severe ipoplasia of myeloid serie, hypereosinophilia and arrest at the promyelocyte stage. No cytogenetic abnormalities were found. He was started on G-CSF therapy with an average dose of 7.5 μg/kg once a day in order to maintain neutrophil count between 1.5 to