Early-onset autosomal dominant distal renal tubular acidosis caused by a de novo SLC4A1 R589C variant with growth failure and rickets.
Hajime Ito, Masumi Nagata, Koji Sakuraya et al.
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Case in brief
A Japanese boy had marked growth failure from 6 months of age and was diagnosed with autosomal dominant distal renal tubular acidosis at 27 months. Evaluation showed metabolic acidosis (pH 7.197, bicarbonate 11.5 mmol/L), hyperchloremia, hypokalemia, hypercalciuria, bilateral nephrocalcinosis, rickets, inappropriately high urine pH, and a positive urinary anion gap. Genetic testing identified a de novo SLC4A1 p.Arg589Cys variant. With alkali therapy, acidosis improved and rickets showed radiographic improvement; substantial catch-up growth occurred over 5 years, while renal function remained preserved.
What made this case unusual
The case highlights infant-onset SLC4A1-associated autosomal dominant disease, which typically presents later and more mildly; severe growth failure was the predominant feature.
Diagnostic / clinical pearl
In a child with otherwise unexplained severe growth failure, assess acid–base status: metabolic acidosis may reveal distal renal tubular acidosis even when growth impairment dominates the presentation.