C1q nephropathy in a patient with Gitelman syndrome

Area of Science:

• Nephrology
• Genetics
• Pathology

Background:

• Bartter syndrome and Gitelman syndrome are rare inherited renal tubulopathies.
• These conditions are typically associated with electrolyte imbalances and can rarely occur with glomerular diseases.
• The co-occurrence is more frequently reported in pediatric populations.

Observation:

• A 50-year-old woman with a 30-year history of Gitelman syndrome presented with newly developed nephrotic syndrome.
• Renal biopsy showed juxtaglomerular apparatus hyperplasia and mesangial C1q deposits.
• No clinical or serological signs of systemic lupus erythematosus were present.

Findings:

• This case represents the first reported instance of adult Gitelman syndrome associated with C1q nephropathy causing nephrotic syndrome.
• The findings suggest a potential, previously unreported association between hypokalemic tubular nephropathies and glomerular nephropathies leading to nephrotic syndrome.
• The presence of C1q deposits in the absence of lupus raises questions about alternative pathogenic mechanisms.

Implications:

• This case expands the known clinical spectrum of Gitelman syndrome.
• It suggests a possible link between specific tubular and glomerular kidney diseases, particularly in adults.
• Further research is warranted to explore the underlying mechanisms and prevalence of this association.