[Neurological findings in severe congenital neutropenia with HAX1 mutations]

HAX1 is an anti-apoptotic factor with multiple functions that controls the integrity of the inner mitochondrial membrane potential and interacts with various viruses and cellular proteins. We have already reported that severe congenital neutropenia (SCN) with HAX1mutations produces neurological symptoms. In this report, we studied the correlation between the neurological symptoms and genetic mutations in all reported cases of HAX1-deficient SCN, including our five cases. Twelve of the 40 patients with HAX-1-deficient SCN had cognitive impairment and ten of these 12 patients suffered from epilepsy. Based on transcription, HAX1 has two isoforms:isoforms a and b. Neurological symptoms were found in HAX1-deficient patients with mutations in the HAX1 gene affecting both transcript variants, while they were not found in those affecting isoform a only. These results suggest that impairment of both of HAX1 isoforms leads to neurological dysfunction.