Bartter syndrome complicated by immune complex nephropathy

Abstract

The unusual coincidence of Bartter syndrome and C1q nephropathy is described and the literature reviewed. An African-American girl presented at 4 years of age with acute hyponatremic dehydration and failure to thrive. Persistent hypokalemic alkalosis and secondary hyperaldosteronism were found. The case was atypical for Bartter syndrome in that proteinuria (0.19 g/day) was present. Renal biopsy showed juxtaglomerular hyperplasia and C1q nephropathy. Molecular analysis showed deletion of the renal chloride channel gene (CLCNKB) typical of autosomal recessive childhood Bartter syndrome. Chronic sodium and potassium chloride replacement therapy together with indomethacin normalized her metabolic status, and she experienced catch-up growth. Proteinuria persisted, however. This is the first documentation of C1q nephropathy, in mild form, complicating autosomal recessive Bartter syndrome. This case shows the importance of the renal biopsy and of molecular analysis in delineating the cause of atypical nephropathy associated with Bartter syndrome. These findings add to the evidence of a possible association between the congenital syndrome and acquired immune complex nephropathy.

C1q nephropathy in association with Gitelman syndrome: a case report

“…A higher prevalence of C1qN in African Americans as compared to Caucasians has been reported by some investigators [16,18,21], but not others [20]. Although it is interesting that both our patient and the child described by Sardani et al are African American [6], it remains unclear whether race is a risk factor for the development of C1qN in these children. Certainly, stimulation of the RAAS has been shown to contribute to the progression of glomerular sclerosis [13] and the hyperexpression of TGFβ has been implicated as one risk factor for renal injury in the African American population [25].…”

“…Two cases of BS and FSGS have been reported, one in a 15-year-old female [1] and one in a 4-year-old girl with a history of bilateral vesicoureteral reflux [5]. C1qN, however, has only been reported once in BS, in a 4-year-old child [6].…”

“…Although neither BS nor GS is classically associated with proteinuria, there have been a few reported cases of concomitant focal segmental glomerulosclerosis (FSGS) [1,4,5]. Recently, Sardani et al described a 4-year-old African American child with BS and mild proteinuria whose renal biopsy revealed findings consistent with C1q nephropathy (C1qN), as well as the expected hyperplasia of the juxtaglomerular apparatus (JGA) which is characteristic of BS [6]. We present an adolescent with GS and proteinuria whose renal biopsy revealed findings consistent with C1qN and GS.…”

C1q nephropathy in two young sisters

“…C1qNP has been reported in association with Gitelman syndrome [15], Bartter syndrome [16], chromosome 13 deletion [17] and severe atopic dermatitis [18]. Those associations between different syndromes and C1qNP could be explained by genetic predisposition.…”

The Heterogeneity and Controversy of C1q Nephropathy: A Report of Two Cases and Review of the Literature

“…C1qN has been reported in association with Bartter syndrome [14], Gitelman syndrome [15] and in a case of chromosome 13 deletion with retinoblastoma [16]. C1qN development in early childhood was also reported in two siblings [17].…”