Associations with various genes (NPHS1, ACTN4, NPHS2, WT-1) and linkage to several chromosomal regions (such as 19q13, 11q21, 11q24) have been reported in patients with familial NS/FSGS.
Our results allowed us to assign a disease locus (SRN1) to a defined chromosomal region on 1q25-1q31, thus confirming the existence of a distinct entity of autosomal recessive nephrosis.
Homozygous or compound heterozygous mutations in the podocin gene NPHS2 are found in 10-30% of pediatric cases of steroid resistant nephrosis and/or FSGS.
Nevertheless, the available data suggest that large epidemiological case-control studies to examine the association between NPHS2 variants and nephrotic syndrome are warranted.
Of the autosomal recessive and the sporadic cases, 13 and 6%, respectively, were found to have podocin-associated nephrotic syndrome, and 56% of them were compound heterozygous for the nonneutral p.R229Q polymorphism.
Gain-of-function mutations in the transient receptor potential (TRP) cation channel subfamily C member 6 (TRPC6) gene and mutations in the NPHS2 gene encoding podocin result in nephrotic syndromes.
Rare mutations in nephrosis 2 (NPHS2), encoding podocin, are found in patients with familial and sporadic steroid-resistant nephrotic syndrome and focal segmental glomerular sclerosis.
The results demonstrate that NPHS1 and NPHS2 mutations are also present in Chinese sporadic NS patients, suggesting that genetic changes of nephrin and podocin may play pathogenetic roles in some patients with sporadic steroid resistant NS.
Of the 38 Hungarian patients screened, seven carried NPHS2 mutations on both alleles, of whom two-diagnosed with proteinuria through school screening programs at the age of 9.7 and 14 years, respectively-did not develop nephrotic syndrome in childhood.
NPHS2 mutations were the most frequent cause of nephrotic syndrome among both families with congenital nephrotic syndrome (39.1%) and infantile nephrotic syndrome (35.3%), whereas NPHS1 mutations were solely found in patients with congenital onset.
In conclusion, the inducible R140Q-podocin mouse model is an auspicious model of the most common genetic cause of human nephrotic syndrome, with a spontaneous disease course strongly reminiscent of the human disorder.
Twelve previously identified podocin mutations were screened by the electronic microarray method in known DNA samples and in patients (aged 5 months-18 years, n = 38) with steroid-resistant primary nephrotic syndrome, isolated proteinuria, end-stage renal disease secondary to idiopathic nephrotic syndrome, and proteinuria relapses following renal transplantation.
Overall, data are here presented that underscore a major role of inherited defects of NPHS2 in NS in children (including a relevant impact in sporadic cases) and give the functional rationale for the association.
The serum alpha 2M concentration was increased approximately equal to 50-fold and was proportional to synthesis (r = 0.91 P < 0.001). alpha 2-Macroglobulin synthesis increased by 12-fold in NAR and 50-fold in NS.
This study identifies GPC5 as a new susceptibility gene for nephrotic syndrome and implicates GPC5 as a promising therapeutic target for reducing podocyte vulnerability in glomerular disease.