Exome sequencing in HFE C282Y homozygous men with extreme phenotypes identifies a GNPAT variant associated with severe iron overload.

Abstract

UNLABELLED:

To identify polymorphisms associated with variability of iron overload severity in HFE-associated hemochromatosis, we performed exome sequencing of DNA from 35 male HFE C282Y homozygotes with either markedly increased iron stores (n = 22; cases) or with normal or mildly increased iron stores (n = 13; controls). The 35 participants, residents of the United States, Canada, and Australia, reported no or light alcohol consumption. Sequencing data included 82,068 single-nucleotide variants, and 10,337 genes were tested for a difference between cases and controls. A variant in the GNPAT gene showed the most significant association with severe iron overload (P = 3 × 10(-6) ; P = 0.033 by the likelihood ratio test after correction for multiple comparisons). Sixteen of twenty-two participants with severe iron overload had glyceronephosphate O-acyltransferase (GNPAT) polymorphism p.D519G (rs11558492; 15 heterozygotes, one homozygote). No control participant had this polymorphism. To examine functional consequences of GNPAT deficiency, we performed small interfering RNA-based knockdown of GNPAT in the human liver-derived cell line, HepG2/C3A. This knockdown resulted in a >17-fold decrease in expression of the messenger RNA encoding the iron-regulatory hormone, hepcidin.

CONCLUSION:

GNPAT p.D519G is associated with a high-iron phenotype in HFE C282Y homozygotes and may participate in hepcidin regulation.

• Authors: Christine E McLaren, Mary J Emond, V Nathan Subramaniam, Pradyumna D Phatak, James C Barton, Paul C Adams, Justin B Goh, Cameron J McDonald, Lawrie W Powell, Lyle C Gurrin, Katrina J Allen, Deborah A Nickerson, Tin Louie, Grant A Ramm, Gregory J Anderson, Gordon D McLaren
• Journal: Hepatology (Baltimore, Md.) (Hepatology) Vol. 62 Issue 2 Pg. 429-39 (Aug 2015) ISSN: 1527-3350 [Electronic] United States
• PMID: 25605615 (Publication Type: Comparative Study, Journal Article)
• Copyright: © 2015 by the American Association for the Study of Liver Diseases.

Chemical References

• HFE protein, human
• Hemochromatosis Protein
• Histocompatibility Antigens Class I
• Membrane Proteins
• RNA, Small Interfering
• Ferritins
• Acyltransferases
• glycerone-phosphate O-acyltransferase

Topics

• Acyltransferases (genetics)
• Alleles
• Analysis of Variance
• Blotting, Western
• Case-Control Studies
• Exome (genetics, physiology)
• Ferritins (blood)
• Genetic Variation
• Hemochromatosis (genetics, physiopathology)
• Hemochromatosis Protein
• Hep G2 Cells
• Histocompatibility Antigens Class I (genetics)
• Homozygote
• Humans
• Iron Overload (genetics, physiopathology)
• Liver Cirrhosis (genetics, physiopathology)
• Male
• Membrane Proteins (genetics)
• Phenotype
• Point Mutation
• RNA, Small Interfering (genetics)
• Real-Time Polymerase Chain Reaction (methods)
• Sequence Analysis, Protein
• Severity of Illness Index