Familial focal segmental glomerulosclerosis with PLCE1 mutation in siblings

A broad clinical spectrum of PLCε1-related kidney disease and intrafamilial variability

BACKGROUND

The phenotypic and genotypic spectrum and kidney outcome of PLCε1-related kidney disease are not well known. We attempted to study 25 genetically confirmed cases of PLCε1-related kidney disease from 11 centers to expand the clinical spectrum and to determine the relationship between phenotypic and genotypic features, kidney outcome, and the impact of treatment on outcome.

METHODS

Data regarding demographics, clinical and laboratory characteristics, histopathological and genetic test results, and treatments were evaluated retrospectively.

RESULTS

Of 25 patients, 36% presented with isolated proteinuria, 28% with nephrotic syndrome, and 36% with chronic kidney disease stage 5. Twenty patients underwent kidney biopsy, 13 (65%) showed focal segmental glomerulosclerosis (FSGS), and 7 (35%) showed diffuse mesangial sclerosis (DMS). Of the mutations identified, 80% had non-missense, and 20% had missense; ten were novel. No clear genotype-phenotype correlation was observed; however, significant intrafamilial variations were observed in three families. Patients with isolated proteinuria had significantly better kidney survival than patients with nephrotic syndrome at onset (p = 0.0004). Patients with FSGS had significantly better kidney survival than patients with DMS (p = 0.007). Patients who presented with nephrotic syndrome did not respond to any immunosuppressive therapy; however, 4/9 children who presented with isolated proteinuria showed a decrease in proteinuria with steroids and/or calcineurin inhibitors.

CONCLUSION

PLCε1-related kidney disease may occur in a wide clinical spectrum, and genetic variations are not associated with clinical presentation or disease course. However, clinical presentation and histopathology appear to be important determinants for prognosis. Immunosuppressive medications in addition to angiotensin-converting enzyme inhibitors may be beneficial for selected patients. "A higher resolution version of the Graphical abstract is available as Supplementary information".

Crumbs homolog 2 mutation in two siblings with steroid-resistant nephrotic syndrome: Two case reports

BACKGROUND

Crumbs homolog 2 (CRB2) is a recently discovered gene that is closely related to the maintenance of normal polarity in podocytes; mutations can directly lead to steroid-resistant nephrotic syndrome (SRNS). However, the characteristics of nephrotic syndrome (NS) caused by CRB2 mutations have not been described.

CASE SUMMARY

We report a novel compound heterozygous mutation of the CRB2 gene in two siblings with SRNS. The two siblings had edema, proteinuria, hypoproteinemia and hyperlipidemia. Both their father and mother had normal phenotypes (no history of NS). Whole exon sequencing (WES) of the family showed a novel compound heterozygous mutation, c.2290 (exon 8) C > T and c.3613 (exon 12) G > A. Glucocorticoid therapy (methylprednisolone pulse therapy or oral prednisone) and immunosuppressive agents (tacrolimus) had no effect. During a 3-year follow-up after genetic diagnosis by WES, proteinuria persisted, but the patient was healthy.

CONCLUSION

CRB2 mutations related to SRNS often occur in exons 7, 10, and 12. Clinical manifestations of SRNS caused by CRB2 mutations are often less severe than in other forms of SRNS.