Cystic fibrosis and Helicobacter pylori gastritis, megaloblastic anaemia, subnormal mentality and minor anomalies in two siblings: a new syndrome?

Cystic fibrosis gene mutation reduces epithelial cell acidification and injury in acid-perfused mouse duodenum

BACKGROUND & AIMS

Dysfunction of the cystic fibrosis transmembrane regulator (CFTR) is associated with diminished duodenal HCO3- secretion, despite a reported lack of clinical duodenal ulceration in affected subjects. We hypothesized that duodenal epithelial cells expressing a mutant CFTR have enhanced resistance to acid-induced injury. To test this hypothesis, we measured duodenal epithelial cell intracellular pH (pHi), injury, and acid back-diffusion in response to a luminal acid challenge in transgenic mice.

METHODS

A murine colony was established for the CFTR DeltaF508 (DeltaF) mutation. Epithelial cell pH i was measured by microscopy with a trapped, fluorescent pH-sensitive dye in living C57BL/6 and DeltaF/DeltaF, +/DeltaF, and +/+ mice. In vivo confocal microscopy confirmed the localization of the dye in the cytoplasm of the epithelial cells. Epithelial injury was measured fluorometrically using propidium iodide. Duodenal epithelial bicarbonate secretion and proton permeability were measured by back-titration. Bicarbonate secretion and acid back-diffusion were measured in a perfused duodenal loop.

RESULTS

Basal and post-acid exposure bicarbonate secretion were reduced in DeltaF/DeltaF mice, although acid back-diffusion was similar to controls. Epithelial pHi of CFTR DeltaF/DeltaF mice during luminal acid exposure was significantly higher than pHi in +/DeltaF, +/+, or C57BL/6 mice. Acid-related epithelial injury was markedly less in DeltaF/DeltaF mice in comparison with the other groups.

CONCLUSIONS

Increased cellular buffering power of the epithelial cells of DeltaF/DeltaF mice likely protects against acidification and injury during acid exposure. We speculate that this protective mechanism partially underlies the perceived relative lack of peptic ulceration in patients affected by cystic fibrosis.

Prevalence of Helicobacter pylori in people with intellectual disability in a residential care centre in Israel

In 1982, Helicobacter pylori (formerly Campylobacter pylori) was identified as a pathogenic factor in peptic ulcer disease by researchers from Australia. Because only a small number of studies of H. pylori infection have been conducted in people with intellectual disability (ID), and none of these were done in Israel, the present authors decided to conduct a pilot study on its prevalence in this population. The Israeli Division for Mental Retardation provides services to over 6000 people in 54 residential care centres (or institutions), and one centre in the south of the country with kibbutz-style living arrangements was selected for this pilot study. The study was performed as part of the yearly routine medical examination of all residents, and blood specimens were drawn for IgG antibodies to H. pylori (ELISA). Out of the 47 individuals screened, 75% (n=36) were seropositive. In addition to the reported high rates of H. pylori infection in residents with ID living in large facilities, the present pilot study suggests that people with ID living in smaller, kibbutz-style arrangements are also at high risk.

Autosomal recessive disorders among Arabs: an overview from Kuwait

Kuwait has a cosmopolitan population of 1.7 million, mostly Arabs. This population is a mosaic of large and small minorities representing most Arab communities. In general, Kuwait's population is characterized by a rapid rate of growth, large family size, high rates of consanguineous marriages within the Arab communities with low frequency of intermarriage between them, and the presence of genetic isolates and semi-isolates in some extended families and Bedouin tribes. Genetic services have been available in Kuwait for over a decade. During this time it has become clear that Arabs have a high frequency of genetic disorders, and in particular autosomal recessive traits. Their pattern is unique and some disorders are relatively common. Examples are Bardet-Biedl and Meckel syndromes, phenylketonuria, and familial Mediterranean fever. A relatively large number of new syndromes and variants have been delineated in Kuwait's population, many being the result of homozygosity for autosomal recessive genes that occurred because of inbreeding. Some of these syndromes have subsequently been found in other parts of the world, negating the concept of the private syndrome. This paper provides an overview of autosomal recessive disorders among the Arabs in Kuwait from a personal perspective and published studies, and highlights the need for genetic services in Arab countries with the goal of prevention and treatment of genetic disorders.