A Premature Baby with Severe Oligohydramnios and Hypotension: a Case Report of Renal Tubular Dysgenesis

Abstract

Renal tubular dysgenesis (RTD) is a rare fatal disorder in which there is poor development of proximal tubules, leading to oligohydramnios and the Potter sequences. RTD occurs secondary to renin-angiotensin system (RAS) blockade during the early stages of fetal development or due to autosomal recessive mutation of genes in the RAS pathway. A boy born at 33+1 weeks due to cord prolapse was found to be anuric and hypotensive. Pregnancy was complicated by severe oligohydramnios from gestational age 28+4 weeks. Abdominal sonography revealed diffuse globular enlargement of both kidneys with increased cortical parenchymal echogenicity. Infantogram showed a narrow thoracic cage and skull X-ray showed large fontanelles and wide sutures suggestive of ossification delay. Basal plasma renin activity was markedly elevated and angiotensin-converting enzyme was undetectable. Despite adequate use of medications, peritoneal dialysis, and respiratory support, he did not recover and expired on the 23rd day of life. At first, autosomal recessive polycystic kidney disease was suspected, but severe oligohydramnios along with refractory hypotension, anuria, skull ossification delay and high renin levels made RTD suspicious. ACE gene analysis revealed compound heterozygous pathogenic variations of c.1454.dupC in exon 9 and c.2141dupA in exon 14, confirming RTD. Based on our findings, we propose that, although rare, RTD should be suspected in patients with severe oligohydramnios and refractory hypotension.

Keywords: Hypotension; Oligohydramnios; Premature Birth; Renal Tubular Dysgenesis.

Fig. 1. The simple X-ray images of the patient showing characteristics of RTD. (A) Initial infantogram showing narrowing thoracic cage with the intubated state. (B) Large fontanelle and wide suture suggesting ossification delay.

Fig. 2. Kidney sonography of the patient (the upper row: right kidney, the lower row: left kidney). (A) At the next day after birth, sonography showed diffuse globular enlargement of both kidneys (right kidney 4.6 cm and left kidney 4.7 cm) with increased cortical parenchymal echogenicity. (B) Third day of birth, newly-occurred multiple dot-like or linear echogenic spots (white arrow heads) were found in the both kidney. (C) Also, new bilateral small perinephric fluid collection (white arrow) and segmental obliterations of IVC in intrahepatic and suprarenal segment were detected, suggesting thrombi in the IVC (black arrow heads).

IVC = inferior vena cava.

Fig. 3. The result of genetic analysis showing variations in ACE gene. (A) A heterozygous c.1454dupC in exon 9 (p.Ser486Phefs). (B) A heterozygous c.2141dupA in exon 14 (p.Asn714Lysfs).

Fig. 4. The changes of patient's mean blood pressure associated with interventions such as inotropes, volume repletion or PD. 5% albumin (green arrows), normal saline (blue arrows), and blood (red arrow heads for red blood cell and white arrow heads for fresh frozen plasma) was used for volume repletion.

HCS = hydrocortisone, PD = peritoneal dialysis.