Dominant inhibition of Fas ligand-mediated apoptosis due to a heterozygous mutation associated with autoimmune lymphoproliferative syndrome (ALPS) Type Ib.

BACKGROUND: Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte homeostasis and immunological tolerance due primarily to genetic defects in Fas (CD95/APO-1; TNFRSF6), a cell surface receptor that regulates apoptosis and its signaling apparatus. METHODS: Fas ligand gene mutations from ALPS patients were identified through cDNA and genomic DNA sequencing. Molecular and biochemical assessment of these mutant Fas ligand proteins were carried out by expressing the mutant FasL cDNA in mammalian cells and analysis its effects on Fas-mediated programmed cell death. RESULTS: We found an ALPS patient that harbored a heterozygous A530G mutation in the FasL gene that replaced Arg with Gly at position 156 in the protein's extracellular Fas-binding region. This produced a dominant-interfering FasL protein that bound to the wild-type FasL protein and prevented it from effectively inducing apoptosis. CONCLUSION: Our data explain how a naturally occurring heterozygous human FasL mutation can dominantly interfere with normal FasL apoptotic function and lead to an ALPS phenotype, designated Type Ib.

Outcomes of children treated with tracheostomy and positive-pressure ventilation at home.

BACKGROUND: Long-term outcomes for children who survive on tracheostomy and positive-pressure ventilation (TPPV) at home are not well known. METHODS: A retrospective review of 20 years of clinical data at a single institution was performed. Outcome measures included 5-year survival, decannulation rate, and neurocognition. RESULTS: A total of 91 children were categorized under neuromotor dysfunction (52%), chronic lung disease (29%), and congenital anomalies (20%). The 5-year survival rates for these categories were 89% (95% confidence interval [CI] = 80%-99%), 76% (95% CI = 57%-100%), and 94% (95% CI = 83%-100%), respectively. Overall, the 5-year decannulation rate was 25% (95% CI = 14%-35%), with children with chronic lung disease having the highest rate (51%). It was found that 14% were extremely delayed in neurocognition. CONCLUSION: Most children on TPPV at home survive beyond 5 years, and a significant number are decannulated. Primary care physicians and communities should be prepared to accommodate the increasing number of children on TPPV at home.

Effects of megestrol acetate on weight gain, body composition, and pulmonary function in patients with cystic fibrosis.

OBJECTIVES: Malnutrition is a negative prognostic indicator in patients with cystic fibrosis (CF) and may accentuate pulmonary decline. We tested whether megestrol acetate would have beneficial effects on growth in patients with CF and pancreatic insufficiency. STUDY DESIGN: We performed a randomized, double-blind, placebo controlled study. All patients were taking replacement enzymes to compensate for pancreatic insufficiency. Patients (n = 17) were randomly assigned to receive either megestrol acetate or placebo. RESULTS: The treatment group had a significant increase in weight-for-age z scores compared with placebo and reached 100% of their ideal body weight within 3 months of initiating therapy. Weight gain included both fat and fat-free mass. Improved pulmonary function (forced vital capacity and forced expiratory volume in 1 second) was noted in the treatment group compared with placebo (P <.04). Reversible adrenal suppression was observed in the majority of patients who received megestrol acetate. CONCLUSIONS: Short-term use of megestrol acetate results in significant weight gain and improved pulmonary function in malnourished subjects with CF. Our study provides a controlled basis for this intervention, identifies important side effects, and provides the foundation for multiyear, longitudinal trials in a larger number of patients with CF.