IgA nephropathy: the presence of familial disease does not confer an increased risk for progression.
BACKGROUND
Immunoglobulin A (IgA) nephropathy is the most common form of glomerulonephritis worldwide. Familial and sporadic cases are recognized, and a locus associated with the familial form of the disease was mapped to chromosome 6. Recent data suggest the familial IgA nephropathy form may have a poorer outcome than the sporadic form.


METHODS
We tested the hypothesis of unequal survival rates between the 2 forms of disease by analyzing time from biopsy to end-stage renal disease in patients of Italian ancestry; 589 patients with sporadic and 96 patients with familial IgA nephropathy.


RESULTS
Overall 10- and 20-year renal survival probabilities of the cohort as a whole were 71% and 50%, respectively. Macroscopic hematuria was the modality of clinical presentation in 51% of patients with familial IgA nephropathy and 39% of patients with sporadic IgA nephropathy. At univariable analysis, the sporadic form of IgA nephropathy was associated significantly with increased risk for renal death. However, patients with the sporadic form tended to be more hypertensive and diagnosed later, with signs of more advanced renal disease than those with familial disease at baseline. In the regression model, form of disease lost any independent effect. Only male sex, lower baseline glomerular filtration rate, greater proteinuria, and histopathologic score proved to be independent predictors of disease progression. Treatment with steroids or angiotensin-converting enzyme inhibitors was associated with improved outcomes.


CONCLUSIONS
Our study does not confirm that familial IgA nephropathy has a worse prognosis than the sporadic form. The similar renal phenotype may support a common pathogenic mechanism underlying familial and sporadic IgA nephropathy.
Izzi
Claudia
C
Divisione di Nefrologia, Università e Spedali Civili, Brescia, Italy.
Ravani
Pietro
P
Torres
Diletta
D
Prati
Elisabetta
E
Viola
Battista Fabio
BF
Guerini
Simona
S
Foramitti
Marina
M
Frascà
Giovanni
G
Amoroso
Antonio
A
Ghiggeri
Gian Marco
GM
Schena
Francesco Paolo
FP
Scolari
Francesco
F
D000328:Adult; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005922:Glomerulonephritis, IGA / Q000150:complications / Q000235:genetics* / Q000401:mortality; D006801:Humans; D007676:Kidney Failure, Chronic / Q000209:etiology / Q000235:genetics* / Q000401:mortality; D008297:Male; D010641:Phenotype; D012307:Risk Factors; D015996:Survival Rate