USB1 and Decreased total neutrophil count: Due to growth retardation, poikiloderma-like skin lesions on face, neck and limbs, nail dystrophy, hypotrichosis and recurrent infections the USB1 (OMIM*613276) gene, responsible for Poikiloderma with Neutropenia (PN; OMIM#604173) [15] was tested, but no mutations were detected.