Male preponderance of patients testing positive for malignant hyperthermia susceptibility.
BACKGROUND
Malignant hyperthermia susceptibility is diagnosed using an in vitro contracture test (IVCT). In families in which the mutation is known, genetic tests are also available. The inheritance pattern is regarded as autosomal dominant, which predicts equal proportions of men and women affected. The aim of this study was to investigate whether there were sex differences in the diagnostic outcome of the 1407 patients tested for malignant hyperthermia in Sweden between 1985 and 2005.


METHODS
Information about sex, diagnosis, IVCT result and kinship was analysed. Comparisons were made between the two sexes. Probands and relatives were analysed separately in order to eliminate bias caused by the type of surgery performed in the two sexes.


RESULTS
Males, more than females, revealed a pathological outcome in IVCT. Amongst male relatives, the fraction of pathological outcome in IVCT was 0.70 [95% confidence interval (CI), 0.66-0.74]; the corresponding value for females was 0.40 (95% CI, 0.36-0.44).


CONCLUSIONS
A significant difference was observed in the sex distribution of outcome of IVCT, with significantly more males revealing a pathological IVCT. This indicates the influence of one or several factors related to sex in the outcome of IVCT, for example different expression of calcium handling proteins in the sexes, a complex pattern of inheritance or unknown environmental factors.
Islander
G
G
Department of Anaesthesia and Intensive Care, MH Unit, Lund University Hospital, SE-221 85 Lund, Sweden. gunilla.islander@skane.se
Rydenfelt
K
K
Ranklev
E
E
Bodelsson
M
M
D002110:Caffeine; D005190:Family; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006221:Halothane; D006801:Humans; D008297:Male; D008305:Malignant Hyperthermia / Q000175:diagnosis / Q000235:genetics* / Q000503:physiopathology; D009119:Muscle Contraction / Q000235:genetics; D009154:Mutation; D012042:Registries; D012107:Research Design; D012737:Sex Factors; D018709:Statistics, Nonparametric; D013548:Sweden
D002110:Caffeine; D006221:Halothane