(677) Unusual presentation of renal tubular dysgenesis: a case report and review of current literature

Objective: Renal tubular dysgenesis (RTD) is a rare disorder that arises from disruption of the renin-angiotensin system. This condition can result from maternal use of RAS-blocking agents or, more rarely, from a mutation in the genes encoding its components. The most common genes implicated include ACE, REN, AGT, and AGTR1. This condition typically presents as severe oligohydramnios or anhydramnios prior to 22-weeks gestation with subsequent pulmonary hypoplasia and associated Potter sequence.

Study Design: In this report, we present a case of a novel mutation in the Angiotensin II Receptor Type 1 (AGTR1) gene and a review of the current literature.

Results: A female infant born at 36-weeks to a multigravida mother with a history of two prior neonatal demises. The pregnancy was complicated by intrauterine growth restriction and anhydramnios beginning at 28-weeks gestation. Fetal kidneys, renal arteries, and bladder had all been unremarkable on previous imaging. However, upon further review, the fetal kidneys appeared homogenous with poorly differentiated calyces. At birth, the infant was anuric, and renal ultrasound revealed poor corticomedullary differentiation with increased bilateral renal echogenicity. Genetic evaluation of the infant revealed a novel mutation in the AGTR1 gene (c.704dup (p.Asn235Lysfs*28)) as the likely cause of Autosomal-recessive renal tubular dysgenesis (AR-RTD). This mutation is currently a variant of undetermined significance. Parental and sibling genetic analysis is currently pending. However, if this mutation is present, it would reclassify this variant as pathogenic.

Conclusion: RTD most often presents with severe oligohydramnios prior to 22-weeks gestation, leading to severe pulmonary hypoplasia and Potter sequence. This, however, is not universal. A better understanding of the correlation between genotype and phenotype could help guide medical decision making and treatment for these infants. A potential new pathogenic mutation for AR-RTD may also be recognized.