Steroid-Resistant Nephrotic Syndrome: Sequencing Panel

Create a PDF of this page

Condition Description

Nephrotic syndrome is a collection of signs and symptoms that occur when glomeruli (the filtering units of the kidneys) leak protein into the urine. Clinical findings include increased proteinuria, edema (swelling), hyperlipidemia, and hypoalbuminemia. Nephrotic syndrome is one of the most commonly diagnosed kidney diseases in childhood and can occur in adulthood. Every year, 2-4 out of every 100,000 children and 3 out of every 100,000 adults are diagnosed with primary nephrotic syndrome in North America.

Nephrotic syndrome can present as an isolated finding or in association with nephritis syndrome or another syndrome. Several diseases may cause nephrotic syndrome and prognosis varies depending on causation. Primary causes include minimal-change nephropathy, focal glomerulosclerosis, membranous nephropathy, and hereditary nephropathies. Secondary causes include diabetes mellitus, lupus erythematosus, viral infections, and preeclampsia. Progressive forms of nephrotic syndrome can lead to chronic kidney disease and/or end-stage renal disease.
 
Genetic disorders account for the majority of cases of nephrotic syndrome that begin within the first year of life and in childhood. Treatment may be available depending on causation of the syndrome, and/or underlying genetic defect. Identification of mutations may modify genetic counseling and recurrence risks after renal transplantation. Phenotypic variation has been demonstrated in patients with the same mutations and/or mutations within the same gene. When a hereditary disorder is suspected, age of onset, presence of extrarenal abnormalities, and type of renal histologic lesions should be considered to determine the appropriate gene(s) to test.

References:
  1. NephCure Kidney International at: http://www.nephcure.org.
  2. Medscape (Pediatric Nephrotic Syndrome and Nephrotic Syndrome)
  3. Benoit G et al. Hereditary nephrotic syndrome: a systematic approach for genetic testing and a review of associated podocyte gene mutations. Pediatr Nephrol. 2010 Sep; 25(9): 1621–1632.
  4. Gigante M et al. Molecular and Genetic Basis of Inherited Nephrotic Syndrome. Int J Nephrol. 2011; 2011: 792195.

Genes (27)

Indications

The test is indicated for:
  • Individuals with a clinical diagnosis of nephrotic syndrome.

Methodology

Next Generation Sequencing: In-solution hybridization of all coding exons is performed on the patient's genomic DNA. Although some deep intronic regions may also be analyzed, this assay is not meant to interrogate most promoter regions, deep intronic regions, or other regulatory elements, and does not detect single or multi-exon deletions or duplications. Direct sequencing of the captured regions is performed using next generation sequencing. The patient's gene sequences are then compared to a standard reference sequence. Potentially causative variants and areas of low coverage are Sanger-sequenced. Sequence variations are classified as pathogenic, likely pathogenic, benign, likely benign, or variants of unknown significance. Variants of unknown significance may require further studies of the patient and/or family members.

Due to pseudogenes, exons 8-10 and exons 20-22 of the CFH gene and exons 41-50 and exons 63-67 of the CUBN gene cannot be analyzed at this time.

Detection

Next Generation Sequencing: Clinical Sensitivity: Unknown. Mutations in the promoter region, some mutations in the introns and other regulatory element mutations cannot be detected by this analysis. Large deletions/duplications will not be detected by this analysis. Results of molecular analysis should be interpreted in the context of the patient's clinical/biochemical phenotype.

Analytical Sensitivity: ~99%.

Specimen Requirements

Submit only 1 of the following specimen types

Preferred specimen type: Whole Blood

Type: Whole Blood

Specimen Requirements:

In EDTA (purple top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml.

Specimen Collection and Shipping: Ship sample at room temperature with overnight delivery.

Type: Isolated DNA

Specimen Requirements:

In microtainer: 60 ug

Isolation using the QiagenTM Puregene kit for DNA extraction is recommended.

Specimen Collection and Shipping:

How to Order

Requisition Forms