In utero intervention in a patient with prune-belly syndrome and severe urethral hypoplasia

Clinical features, genetic background, and outcome in infants with urinary tract infection and type IV renal tubular acidosis

BACKGROUND

Type IV renal tubular acidosis (RTA) is a severe complication of urinary tract infection (UTI) in infants. A detailed clinical and molecular analysis is still lacking.

METHODS

Infants with UTI who exhibited features of type IV RTA were prospectively enrolled. Clinical, laboratory, and image characteristics and sequencing of genes responsible for phenotype were determined with follow-up.

RESULTS

The study cohort included 12 infants (9 males, age 1-8 months). All exhibited typical type IV RTA such as hyperkalemia with low transtubular potassium gradient, hyperchloremic metabolic acidosis with positive urine anion gap, hypovolemic hyponatremia with renal salt wasting, and high plasma renin and aldosterone levels. Seven had hyperkalemia-related arrhythmia and two of them developed life-threatening ventricular tachycardia. With prompt therapy, all clinical and biochemical abnormalities resolved within 1 week. Five had normal urinary tract anatomy, and three of them carried genetic variants on NR3C2. Three variants, c.1645T>G (S549A), c.538G>A (V180I), and c.1-2C>G, on NR3C2 were identified in four patients. During follow-up, none of them had recurrent type IV RTA, but four developed renal scaring.

CONCLUSIONS

Genetic mutation on NR3C2 may contribute to the development of type IV RTA as a complication of UTI in infants without identifiable risk factors, such as urinary tract anomalies.

Prune-belly syndrome: an autopsy case report

Prune-belly syndrome (PBS) is a rare congenital anomaly characterized by a spectrum of mild-to-severe presentations of urinary tract malformations, deficient abdominal wall musculature, and cryptorchidism in male newborns or genital abnormalities in the female newborns. Currently, antenatal diagnosis is feasible with ultrasound examination, and treatment is based on case report experience. More recently, intrauterine management has been undertaken with encouraging results. The authors report a case of PBS diagnosed at the seventeenth gestation week, when ultrasonographic examination revealed the presence of ascites, distended bladder, thickened bladder wall and posterior urethral valve. The fetus was submitted to an intrauterine intervention at the nineteenth gestational week. Delivery occurred at 34 weeks of gestation and the newborn examination was consistent with PBS. On the second day of life, the newborn was submitted to abdominoplasty, colostomy, and orchiopexy. However, the outcome was unfavorable with respiratory failure and death on the fifteenth day of life. The autopsy confirmed the diagnosis of PBS, but the immediate cause of death was attributed to aspiration pneumonia.