Nephrotic Syndrome: Type 1

Nephrotic syndrome type 1 (NPHS1), also called congenital nephrotic syndrome of the Finnish, is an inherited disorder that causes progressive kidney disease. Affected children are usually born prematurely and kidney damage is usually present at birth or develops within the first few months of life. Additional symptoms include fluid accumulation inside the body, hypertension, high levels of protein in urine and low levels of protein in the blood. This syndrome is resistant to steroid therapy. Progressive kidney disease usually leads to end-stage renal failure and death within the first decade of life. Kidney transplant is curative, although there is a risk of recurrence of kidney disease after transplantation. Intellect is not affected by NPHS1. NPHS1 is due to pathogenic variants in the NPHS1 gene.

NPHS1 is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for NPHS1. However, the risk to have a child affected with NPHS1 is increased. Testing of reproductive partners is recommended for carriers of NPHS1.

NPHS1 is more common in the Finland population and their descendents, and Old Order Mennonites in Eastern Pennsylvania. Nephrotic syndrome type 1 affects 1 in 8,000 newborns in Finland.

Genetics Home Reference: NPHS1 (http://ghr.nlm.nih.gov/)
Orphanet: Congenital nephrotic syndrome, Finnish type (https://www.orpha.net/)

OMIM [Nephrotic Syndrome Type 1: 256300] (http://www.ncbi.nlm.nih.gov/omim)

• Full gene sequencing