A Phase I Study of Mozobil in the Treatment of Patients With WHIMS

Background: * WHIMS (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis Syndrome) is caused by various genetic changes that increase the activity of the chemokine receptor, CXCR4. Excessive function of this receptor causes mature neutrophils (part of the white blood cells) to be retained within the bone marrow rather than being released to the blood and is one of the causes of severe inherited neutropenia (low white blood counts). In neutropenia, the body is less able to fight off infection. Patients with WHIMS usually are at risk for skin, soft tissue, sinus, and lung infections, which can result in loss of hearing, teeth, and lung function. * Current treatment for WHIMS consists of regular injections of a white blood cell growth stimulating medication called granulocyte colony stimulating factor (G-CSF), and supplemental immunoglobulin (antibody). These therapies are expensive, nonspecific, have significant side effects and toxicities, and do not fully correct all problems, especially warts and cancers related to human papillomavirus (HPV). * A drug called Mozobil has been approved for use in combination with G-CSF to increase the number of stem cells that can be collected prior to bone marrow transplantation. Mozobil may offer a specific and well-tolerated new treatment for WHIMS and other syndromes characterized by neutropenia. Objectives: * To evaluate whether Mozobil is safe and effective to treat neutropenia (low white blood cell count) in patients with WHIMS. * To determine an appropriate treatment dose of Mozobil, within currently approved dosage levels. Eligibility: \- Individuals between 18 and 75 years of age who have been diagnosed with WHIMS and have a history of severe infections. Design: * Potential participants will undergo a screening with a medical history, physical examination, questionnaire, heart and lung function scans, and blood and urine samples. Tests will also be done for hepatitis B and C virus, and human immunodeficiency virus (HIV) that causes acquired immunodeficiency syndrome (AIDS), as well as to check neutrophil function. * Patients who are being treated with G-CSF will stop injections for 2 days before being admitted to the National Institutes of Health (NIH) Clinical Center. * Patients may participate in a Dose Escalation study and receive increasing doses of Mozobil over 5 days of treatment until their white blood cell count improves sufficiently or the maximum approved dose is reached. Blood samples will be taken regularly throughout the treatment process. Patients will then receive an additional dose of Mozobil at the maximum approved dose or the dose sufficient to cause improvement, before restarting the G-CSF injections. * Patients may also participate in a long-term Chronic Dosing study and receive Mozobil once or twice a day for up to a maximum of 60 months.