Clinical relevance of hemochromatosis-related HFE C282Y/H63D gene mutations in patients on chronic dialysis.
BACKGROUND
The actual prevalence and the clinical relevance of gene mutations of HFE (which are linked to hemochromatosis) have not yet been established in patients on chronic dialysis. On the basis of theoretical premises, it could be hypothesized that these genetic determinants might influence the response to iron intake and the susceptibility for iron overload in patients in parenteral iron therapy. Furthermore, carriers for these mutations might be prone to develop sporadic porphyria cutanea tarda and cardiovascular events.


METHODS
C282Y/H63D mutations of HFE gene were evaluated in 132 patients (34 in peritoneal dialysis, 98 in HD) and correlated with biochemical parameters of iron status (ferritin (FER) concentration and transferrin saturation (TSAT)), red cell parameters (red cell size and hemoglobin content), erythropoietin (EPO) dosage, major cardiovascular events and C-reactive protein as marker of chronic inflammation, in patients without iron therapy and after i.v. iron supplementation (< or = 60 mg/week) and with the presence of biopsy-proven porphyria.


RESULTS
C282Y heterozygous mutation was found in 8/132 (6.6%); H63D homozygous and heterozygous mutations were found in 3/132 (2.3%) and 22/132 (16%) patients, respectively. Two patients (1.5%) showed double heterozygosis. No differences in baseline serum FER and TSAT and the other biochemical and clinical parameters were found in patients bearing mutations alleles nor after continuous iron therapy at low dosages. However, the prevalence of patients capable of maintaining normal hemoglobin (Hb) level without EPO therapy is increased in the C282Y-mutated patients. Only 1 patient out of the 4 with biopsy-proven porphyria cutanea tarda was bearing gene mutations (H63D heterozygosis).


CONCLUSIONS
C282Y/H63D HFE gene mutations do not seem to be related to major abnormalities in biochemical parameters of iron status in dialysis patients without iron therapy or after i.v. iron supplementation, granted that low dosages are employed. Obviously, as our patients were exposed to a relatively uniform iron regimen in our clinical center (< or = 60 mg/week), it is unclear if other dosing regimens will unmask clinically significant differences between the heterozygotes and normals. The fact that the C282Y-mutated patients more frequently maintain high Hb values without EPO is interesting as could suggest a better use of available iron for erythopoiesis, but needs to be confirmed in larger samples. No clear association is demonstrated with porphyria cutanea tarda and major cardiovascular events.
Canavese
C
C
Section Nephrology, Department of Internal Medicine of the University of Torino, Torino, Italy. ccanavese@hotmail.com
Bergamo
D
D
Barbieri
S
S
Timbaldi
M
M
Thea
A
A
Martina
G
G
Damiani
D
D
Fenoglio
R
R
Donati-Marella
B
B
Priolo
G
G
D000368:Aged; D005260:Female; D006432:Hemochromatosis / Q000235:genetics*; D000071020:Hemochromatosis Protein; D006579:Heterozygote; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D007501:Iron / Q000097:blood; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation; D010530:Peritoneal Dialysis; D017119:Porphyria Cutanea Tarda / Q000235:genetics; D015995:Prevalence; D011990:Receptors, Transferrin / Q000235:genetics; D006435:Renal Dialysis
C103673:HFE protein, human; D000071020:Hemochromatosis Protein; D015395:Histocompatibility Antigens Class I; D008565:Membrane Proteins; D011990:Receptors, Transferrin; D007501:Iron