Plerixafor Versus G-CSF in the Treatment of People With WHIM Syndrome

Background: \- WHIMS (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis Syndrome) is a rare disease. It can cause cancers, infections, and warts. Researchers want to see if a drug called plerixafor can treat WHIMS. Objective: \- To compare plerixafor versus granulocyte colony stimulating factor (G-CSF) for preventing infections in people with WHIMS. Eligibility: \- People ages 10-75 with WHIMS who have a CXCR4 gene mutation. Design: * Participants will be screened with a medical history, physical exam, and blood and urine tests. They may have heart and spleen tests and body scans. They may have samples of skin or warts taken. Researchers may take photographs of warts. * Participants will start twice daily self-injections of G-CSF. Their doctors will decide the dosage. * Initial Period (4-12 weeks) * Participants will: * continue the injections and their usual antibiotics and/or immunoglobulin * have blood drawn * keep a daily health diary * Participants will visit the clinic for 2 days without injections. * Adjustment Period 1 (8 weeks): * Participants will: * continue twice daily injections from home * continue the daily health diary * have blood tests every 2 weeks. * Treatment Year 1: * Participants will * receive either plerixafor or G-CSF injections twice daily * continue the health diary * have blood tests every 2 months * visit the clinic about every 4 months * At the end of year 1, participants will visit the clinic for an evaluation. They will switch to the other study drug. They will have an 8-week adjustment and 1-year treatment period. * At the end of year 2, participants will visit the clinic to complete their injections and go back to their previous G-CSF regimen. Participants will continue their daily health diary and have blood tests for 5-6 months.