Cause and Natural Course of Pediatric-Onset Mastocytosis

Mastocytosis in infants and children is an unusual disease characterized by an excess of mast cells in tissues. In pediatric onset mastocytosis, disease is usually localized to the skin and disease is considered to be of limited duration. However, a subset of children appear to develop a clinical picture resembling that observed in adults who have adult-onset disease. This study will focus on children with more severe mastocytosis in an attempt to define its pathogenesis, focusing on mutations and polymorphisms in genes regulating mast cell proliferation and survival to determine if they might contribute to this disease pattern. If severe pediatric-onset disease does not fit within the existing classification, new criteria of diagnosis must be proposed for the pediatric age group. This study will examine children and young adults age birth to 21 years with pediatric-onset disease previously enrolled on NIAID mastocytosis protocols, or as a result of physician referral, which have disease more consistent with adult-onset disease or parameters associated with increased morbidity. The evaluation may include serum tryptase, blood count, bone marrow biopsy and aspirate, morphology and mutational analysis. Subjects may be asked to return in 12-24 months for assessment. If relevant mutation effecting mast cell growth and function are identified, such mutations will be sought in the biologic parents as appropriate, but only when such mutations are believed to be germ line (not somatic) mutations. This study will aid in the understanding of the characteristics of severe mastocytosis in the pediatric age group.