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Genetic Etiologies of Bilateral Renal Agenesis 

Prenatal Genetics
  • Primary Categories:
    • Prenatal Genetics
  • Secondary Categories:
    • Prenatal Genetics
Introduction:

Bilateral renal agenesis (BRA) with anhydramnios due to fetal anuria has a poor prognosis due to severe pulmonary hypoplasia. Although often isolated, BRA may be one feature of a larger, complex genetic disorder. Our objective was to further elucidate the genetic etiologies of fetuses with BRA.



 



Methods:

We performed a retrospective cohort study of all patients with fetal BRA presenting to an academic medical center for evaluation under the Renal Anhydramnios Fetal Therapy (RAFT) trial over a five-year period. Maternal demographics, ultrasound reports, and genetic screening/diagnostic testing results were reviewed. Pedigrees were also assessed to help inform potential inheritance.



 



Results:

From 2017 – 2022, 52 patients with fetal BRA presented for evaluation. Extrarenal anomalies were seen in 17 (33%), most commonly cardiac (11), CNS (4), and skeletal (4). Aneuploidy screening was performed in 32 (62%), and none screened positive for the common autosomal aneuploidies. Diagnostic testing, offered to all, was completed in 37 patients (71%) with a 19% testing yield (7/37). 25 of the 37 had isolated BRA. Of 14 karyotypes, 1 case of 47,XXX was appreciated. Chromosomal microarray, performed in 28 patients, identified 3 copy number variants (CNVs): (2q21.1 duplication, 16p13.11 duplication, and 22q11.2 microdeletion). Exome sequencing revealed a pathogenic abnormality in 3 out of 5 patients (heterozygous variants in GREB1L and RET, compound heterozygous variants in FREM2). Of 7 patients with abnormal diagnostic testing, only 3 had extrarenal anomalies. Pedigrees were elicited in 46 patients with 13 (28%) reporting a family history of a genitourinary anomaly.



 



Conclusion:

Approximately 1 in 5 fetuses with BRA have abnormal genetic testing. This highlights the importance of a comprehensive diagnostic testing approach in this population. Future research routinely employing molecular methodologies that interrogate for potentially etiologic CNVs and single gene disorders in pregnancies with BRA is needed to further our understanding of this condition, and to better inform parental counseling. 



 



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