Nonradioactive direct sequencing of RT-PCR fragments of the G-CSF receptor cytoplasmic domain in myeloid cells from congenital neutropenia patients. G-CSF receptor cDNA from neutrophils of congenital neutropenia patient MA before (lane 2) and at the time point of diagnosis of AML (lane 3) and from her brother FA, who is also a congenital neutropenia patient, but who has not yet developed AML (lane 1), was amplified with primers Q1 and Q2 and sequenced directly. In each lane, the nucleotides are shown in the following order: GATC. The asterisk indicates the position of the point mutation.