Childhood sleep-disordered breathing and its implications for cardiac and vascular diseases.

OBJECTIVE: To systematically evaluate the recent literature regarding the relationship between childhood sleep-disordered breathing (SDB)/obstructive sleep apnoea (OSA) and cardiovascular diseases in children. METHODS: The literature about SDB/OSA and blood pressure, sympathetic activation, arterial distensibility, ventricular hypertrophy and insulin resistance were studied. Meta-analysis of risk of hypertension and high apnoea-hyponoea index were performed to calculate the combined odds ratio and it is equal to 2.93 (95% CI = 1.18-7.29). RESULTS: The results suggest a significant association between SDB/OSA and hypertension. However, the data are not adequate to draw firm conclusion although evidences were emerging to suggest that SDB/OSA affects blood pressure in either directions in children. Limited evidences also suggest that SDB/OSA is associated with increased sympathetic activation, decreased arterial distensibility and ventricular hypertrophy. CONCLUSIONS: There is now increasing but not adequate evidence that childhood SDB/OSA is associated with detectable cardiovascular abnormalities.

The C282Y mutation of the HFE gene is not found in Chinese haemochromatotic patients: multicentre retrospective study.

OBJECTIVE: To detect two novel mutations (C282Y and H63D) of the HFE gene in Chinese patients with hepatic iron overload. DESIGN: Multicentre retrospective study. SETTING: Four public hospitals, Hong Kong. PARTICIPANTS: Fifty Chinese patients who presented from January 1987 through December 1999 with hepatic iron overload from various causes. MAIN OUTCOME MEASURES: The DNA from liver biopsy samples was tested for HFE mutations by restriction fragment length polymorphism analysis. RESULTS: The sample DNA quality was unsatisfactory for analysis of the C282Y mutation in one case and the H63D mutation in nine cases. The C282Y mutation was not detected in any of the 49 satisfactory samples. Three of the 41 samples were heterozygous for the H63D mutation and only one was homozygous, giving an allele frequency of 6.1%. Of the three H63D-heterozygotes, one had beta-thalassaemia major, one had beta-thalassaemia minor, and one had hereditary spherocytosis. None of the 12 patients who were presumed to have primary haemochromatosis were positive for either mutation. CONCLUSIONS: The classical form of human leukocyte antigen-linked hereditary haemochromatosis appears to be absent form this locality. The H63D mutation is found in a minority (9.8%) of the patients, in whom it may act synergistically with an erythropoietic factor.