A 4-year-old boy presenting with persistent urinary incontinence: Questions.

Area of Science:

• Pediatric Nephrology
• Clinical Genetics

Background:

• A 4-year-old boy presented with daytime urinary incontinence and polyuria/polydipsia, initially suspected as primary polydipsia or diabetes insipidus.
• Previous evaluations, including water deprivation tests and MRI, excluded central diabetes insipidus and diabetes mellitus.

Observation:

• The patient exhibited significant daily fluid intake (up to 3L) and frequent wetting, alongside infrequent, difficult stools.
• A family history of similar symptoms in the grandmother, diagnosed with primary polydipsia, suggested a potential genetic link.

Findings:

• Despite normal urinalysis, renal ultrasound, and a negative desmopressin test, genetic testing identified a missense mutation in the AVPR2 gene (p.Arg104Cys), confirming partial nephrogenic diabetes insipidus.
• Treatment with desmopressin led to rapid resolution of urinary incontinence, polyuria, and fecal incontinence within three days.

Implications:

• This case underscores the importance of comprehensive diagnostic evaluation, especially in pediatric cases with complex symptoms and family history.
• Genetic testing is crucial for diagnosing rare conditions like partial nephrogenic diabetes insipidus, even when initial tests are inconclusive.
• Accurate diagnosis and targeted treatment, such as desmopressin for AVPR2 gene mutations, can significantly improve patient outcomes and quality of life.