Dual Monogenic Cystic Disease Case Report: Autosomal Dominant Polycystic Kidney Disease and Autosomal Dominant Polycystic Liver Disease.

Autosomal dominant polycystic kidney disease (ADPKD) and autosomal dominant polycystic liver disease (ADPLD) are inherited cystic conditions with overlapping features but distinct genetic causes and clinical courses. Here, we report a case of a 50-year-old woman with a clinical diagnosis of ADPKD, hypertension, preserved kidney function, significant abdominal distention consistent with hepatomegaly, and innumerable kidney and hepatic cysts. Family history was remarkable for ADPKD clinical diagnosis in the patient's mother, maternal grandmother, and the grandmother's siblings. Genetic testing with a 385-gene NGS-based kidney disease panel (the Renasight test) identified heterozygous truncating pathogenic variants in PKD1: c.3957_3994dup p.(Asp1332Glyfs*27)) (ClinVar ID VCV003376509.1) and PRKCSH: c.374_375del p.(Glu125fs)) (ClinVarID VCV001048653.34). To our knowledge, this is the first reported case of dual monogenic drivers of ADPKD and ADPLD in a single individual. This report highlights the importance of using unbiased genetic testing in cystic disease evaluation, even when family history suggests a single condition, to inform prognosis, reproductive risk, and accurate cascade testing in relatives.