Spectrum of Perforin Gene Mutations in Familial Hemophagocytic Lymphohistiocytosis

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive disease of early childhood characterized by nonmalignant accumulation and multivisceral infiltration of activated T lymphocytes and histiocytes (macrophages). Cytotoxic T and natural killer (NK) cell activity is markedly reduced or absent in these patients, and mutations in a lytic granule constituent, perforin, were recently identified in a number of FHL individuals. Here, we report a comprehensive survey of 34 additional patients with FHL for mutations in the coding region of the perforin gene and the relative frequency of perforin mutations in FHL. Perforin mutations were identified in 7 of the 34 families investigated. Six children were homozygous for the mutations, and one patient was a compound heterozygote. Four novel mutations were detected: one nonsense, two missense, and one deletion of one amino acid. In four families, a previously reported mutation at codon 374, causing a premature stop codon, was identified, and, therefore, this is the most common perforin mutation identified so far in FHL patients. We found perforin mutations in 20% of all FHL patients investigated (7/34), with a somewhat higher prevalence, ∼30% (6/20), in children whose parents originated from Turkey. No other correlation between the type of mutation and the phenotype of the patients was evident from the present study. Our combined results from mutational analysis of 34 families and linkage analysis of a subset of consanguineous families indicate that perforin mutations account for 20%–40% of the FHL cases and the FHL 1 locus on chromosome 9 for ∼10%, whereas the major part of the FHL cases are caused by mutations in not-yet-identified genes

Renal function and renotropic effects of secretin in cystic fibrosis.

In ten cystic fibrosis patients and nine age-matched controls, renal function was determined before and after infusion of secretin. Under baseline conditions creatinine excretion and clearance were significantly elevated, exclusively due to those patients who were homozygous for the DF508 mutation (153 vs 132 ml/min*1.73m2), whereas the glomerular filtration rate, measured by inulin clearance showed no difference. Renal plasma flow and the fractional reabsorption rates of electrolytes were similar in patients and controls. During secretin infusion renal plasma flow increased and the fractional reabsorption rates of electrolytes decreased in both groups. The patients had a increased metabolic clearance (2900 vs 1660 ml/min*m2) and endogenous production rate (9,9 vs 2,5 pmol/min*m2) of of secretin. In conclusion global renal function and electrolyte handling, in particular chloride permeability, are unchanged in cystic fibrosis. Individuals expressing the DF508 genotype showed a selective elevation of creatinine excretion and clearance. The secretion and metabolic clearance of secretin are increased in cystic fibrosis.link_to_subscribed_fulltex

The association between drinking water turbidity and gastrointestinal illness: a systematic review.

BACKGROUND: Studies suggest that routine variations in public drinking water turbidity may be associated with endemic gastrointestinal illness. We systematically reviewed the literature on this topic. METHODS: We searched databases and websites for relevant studies in industrialized countries. Studies investigating the association between temporal variations in drinking water turbidity and incidence of acute gastrointestinal illness were assessed for quality. We reviewed good quality studies for evidence of an association between increased turbidity and gastrointestinal illness. RESULTS: We found six relevant good quality studies. Of five studies investigating effluent water turbidity, two found no association. Two studies from Philadelphia reported increased paediatric and elderly hospital use on specific days after increased turbidity. A fifth study reported more telephone health service calls on specific days after peak turbidity. There were differences between studies affecting their comparability, including baseline turbidity and adjustment for seasonal confounders. CONCLUSION: It is likely that an association between turbidity and GI illness exists in some settings or over a certain range of turbidity. A pooled analysis of available data using standard methods would facilitate interpretation