Study Identifies Genetic Variation Associated With Increased Risk Of Liver Disease For Patients With Cystic Fibrosis

Main Category: Liver Disease / Hepatitis
Also Included In: Cystic Fibrosis;  Genetics
Article Date: 15 Sep 2009 - 0:00 PDT

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A genetic analysis indicates that a certain gene variation in patients with cystic fibrosis may significantly increase their risk of developing severe liver disease, according to a study in the September 9 issue of JAMA.

A small fraction (about 3 - 5 percent) of patients with cystic fibrosis (CF) develop severe liver disease characterized by cirrhosis with portal hypertension (CFLD; increase in blood pressure caused by obstruction in the liver). Previous research has suggested that genetic variability that is not associated with the cystic fibrosis transmembrane conductance regulator (CFTR) gene may contribute to the risk for severe liver disease.

Jaclyn R. Bartlett, Ph.D., of the University of North Carolina at Chapel Hill, and colleagues examined nine variants in five genes previously studied in CF liver disease to determine the association between non-CFTR genetic variations and CFLD. The initial study compared genetic variations in the candidate genes in persons with CFLD (n = 124) and in control patients without CFLD (n = 843), with a second study testing these findings in different populations of patients with (n = 136) and without (n = 1,088) CFLD.

The researchers found that of the 5 genes studied, "only the SERPINA1 Z allele [an alternative form of a gene] was significantly associated with CFLD and portal hypertension. This polymorphism is relatively uncommon in CF [about 2.2 percent of patients with CF are carriers], but the odds ratio for association with severe liver disease is relatively high [about 5 times higher] for the contribution of a genetic modifier to a mendelian [genetic] disorder. Moreover, the estimated population-attributable risk among patients with CF is 6.7 percent. From a clinical perspective, a rare variant with large penetrance (such as the Z allele) may be more useful than a common variant with low penetrance in screening for genetic polymorphisms."

"The identification of the SERPINA1 Z allele as the first marker for the development of severe liver disease in CF illustrates the possibility of identifying CF risk factors early in life, conceptually as a secondary component of neonatal screening after the diagnosis of CF is confirmed," the authors conclude.

JAMA. 2009;302[10]:1076-1083.

Source
Journal of the American Medical Association