The histopathologic classification of focal and segmental glomerulosclerosis (FSGS) is not necessarily reflective of etiologies. A more clinically useful practice is to classify FSGS into primary, secondary and genetic. Primary FSGS is caused by unknown circulating mediator injurious to podocytes. Secondary FSGS can be further subclassify into maladaptive, viral and drug-induced. Genetic FSGS has many already-identified and unidentified mutations.
Relevant mutation needed to be identified in order to diagnose genetic FSGS, but not all patients with FSGS need genetic test. De Vriese et al. provide useful algorithm for genetic assessment in FSGS patients.
Secondary FSGS in the diagram refers only to maladaptive form. Viral and drug-induced FSGS must be ruled out by presence of infection or drug exposure.
https://doi.org/10.1681/ASN.2017090958
