- Thin basement membrane disease (TBMD).

Thin Basement Membrane Disease

 Thin basement membrane disease (TBMD) is defined by the presence of persistent microscopic hematuria and isolated thinning of the GBM (and, occasionally, tubular basement membranes) on electron microscopy.
Etiology:
TBMD may be sporadic or transmitted as an autosomal dominant trait.
Heterozygous mutations in the COL4A3 and COL4A4 genes, which encode the α3 and α4 chains of type IV collagen present in the GBM, result in TBMD.
Homozygous mutations in these same genes result in autosomal recessive AS. Therefore, in these rare cases, the absence of a positive family history for renal insufficiency or deafness would not necessarily predict a benign outcome. 
Clinical Features:

• Microscopic hematuria is often initially observed during childhood and may be intermittent.
• Episodic gross hematuria can also be present, particularly after a respiratory illness.
• Isolated hematuria in multiple family members without renal dysfunction is referred to as benign familial hematuria.

Routine immunofluorescence studies are normal
Prognosis: good prognosis but in Rare cases of TBMD progress, and such patients develop significant proteinuria, hypertension, or renal insufficiency.
Monitoring patients with benign familial hematuria for progressive proteinuria, hypertension, or renal insufficiency is important through childhood and young adulthood.
Treatment:

• Since TBMN usually has a benign outcome, treatment is rarely indicated.
• Patients with TBMN who have proteinuria are theoretically candidates for angiotensin blockade.

References:

1. Cynthia G. Pan and Ellis D. Avner , nelson textbook of pediatric 20ed ,
2. Ellis d. avner,william e. harmon,patrick niaudet,norishige yoshikawa,francesco emma,stuart l. goldstein, Pediatric Nephrology, 7th ed

Ibrahim Samaha