Notably, the extraordinary finding in our study is the high frequency of mutations in DUOX2 and the autosomal recessive inheritance of this gene, which is not consistent with genetic epidemiology of CH in Caucasian population, in which affected siblings are much less than 25%, whereas our data showed that the frequency affected siblings followed the classic Mendelian autosomal recessive inheritance (both siblings were affected in family 2). Here, DUOX2 is linked to cyclic hematopoiesis.