Unilateral polycystic kidney with PKHD1 gene mutation
Article information
A 19-year-old female visited the outpatient clinic to follow up on kidney imaging. She had been diagnosed with incidental left hydronephrosis which was found at fetal ultrasonography and followed yearly until 6 years old, and she had no medical problems including urinary tract infections. There was no family history of kidney disease including cystic disease and her parents’ kidney sonographic findings were normal. Her physical examination findings, blood and urine tests were all normal.
The sonographic finding when she was 2 years old showed only a 0.6 cm-sized simple cyst in the right kidney and severe hydronephrosis of the left kidney, however, dynamic abdominal and pelvic computed tomography (CT) performed at 19-year-old showed innumerable cysts of the right kidney, and residual mild dilatation of left renal pelvocalyx which was thought the sequelae of previous severe hydronephrosis.
CT showed that the left kidney morphology was normal except for the previously diagnosed mild calyceal dilatation, but a polycystic change was found throughout the total right kidney (Fig. 1). A next-generation sequencing (NGS) for polycystic kidney disease confirmed a heterozygous mutation of c.7769T>G, p.(Met2590Arg) in the PKHD1 gene which was a variant of unknown clinical significance (VUS). PKD1, PKD2, and other PCKD-related gene tests were negative (Table 1).
Abdominopelvic computed tomography image.
It showed that the left kidney morphology was normal except for the previously diagnosed mild calyceal dilatation, but a polycystic change was found throughout the total right kidney.
Mutations in PKHD1 are an important cause of autosomal recessive polycystic kidney disease (ARPKD), but the clinical manifestations are diverse. This case has a heterozygote mutation in PKHD1, but as it is a VUS state, there is no clinical problem and it is expected that there will be no genetic abnormality. It is not sure that the left hydronephrosis found in this case can be assumed as occurring due to the influence of this mutation. However, mutations in PKHD1 were also identified in studies analyzing families of ARPKD patients, and it can be explained that previously reported cases of asymptomatic unilateral polycystic kidney disease in adults are also might be partially associated with PKHD1 [1,2]. However, it is still difficult to explain why polycystic nephropathy occurs in only one kidney, and it is believed that the mechanism can be revealed through additional clinical and genetic experiences.
In this case, the PKHD1 gene mutation was confirmed through NGS analysis in an incidentally found unilateral polycystic kidney. Although the unilateral polycystic kidney is not clinically significant, it is necessary to confirm that it is one of the various heterozygotes of the PKHD1 gene.
This report was approved by the Institutional Review Board of Chungbuk National University Hospital (No. 2023-10-014).
Notes
Conflicts of interest
All authors have no conflicts of interest to declare.
Data sharing statement
The data presented in this study are available from the corresponding author upon reasonable request.
Authors’ contributions
Conceptualization, Investigation: JHP, HYK
Data curation: All authors
Formal analysis: JHP
Methodology: HW, BSC
Supervision: HW, HYK
Writing–original draft: JHP, HW
Writing–review & editing: All authors
All authors read and approved the final manuscript.