Geographical clustering and maintained health in individuals harbouring the mutation for Greenland familial cholestasis: A population-based study.

OBJECTIVE

Cholestasis Familiaris Groenlandica, a severe variant of progressive familial intrahepatic cholestasis type 1 (Byler disease), carries an autosomal recessive trait, and the mutation has been located. The disease is relatively common among Inuit in East Greenland. The aim of the study was to assess the carrier frequency and the possible impact on health in populations in East Greenland.

MATERIAL AND METHODS

A population-based study comprising 324 Inuit and non-Inuit subjects, aged 50-69 years, living in the Ammassalik district of East Greenland was carried out to analyse the presence of the mutation on ATP8B1 at 18q21. Bilirubin and gamma-glutamyl transpeptidase levels in serum were measured, a physical examination was performed, which included body height and weight, and calculation of BMI.

RESULTS

The participation rate was 96%. None of the subjects was homozygous and 12% of Inuit were heterozygous for the mutation. Harbouring the mutation did not influence height (p = 0.26), weight (p = 0.89), BMI (p = 0.65), frequency of self-reported disease (p = 0.17), or differ with gender (p = 0.57). A marked geographical clustering was found (p = 0.002) and heterozygocity for the mutation varied from 5% in a southern to 23% in a northern settlement where 1 out of 75 children could be calculated to have the disease. A physical investigation identified none with jaundice or signs of liver disease. Bilirubin and gamma-glutamyl transpeptidase levels in serum were lower among mutation-positive compared with mutation-negative Inuit.

CONCLUSIONS

Heterozygosity for Greenland familial cholestasis is common among the Inuit in East Greenland but it is not a risk factor for disease in the carrier.