Clinically Significant Genetic Results in Fetuses With Isolated Horseshoe Kidney

OBJECTIVE: To explore genetic investigative results in fetuses with isolated horseshoe kidney (HSK). METHODS: This was a retrospective study of 95 cases with isolated fetal HSK diagnosed on second trimester anatomy ultrasound. All cases underwent invasive prenatal diagnosis for copy number variant (CNV) detection by chromosomal microarray analysis (CMA). For those with a negative CNV, trio exome sequencing (ES) was an option. Clinical and laboratory data were collected and reviewed for these cases, including maternal demographics, prenatal sonographic findings, molecular testing results, and pregnancy outcomes. RESULTS: In total, 95 cases underwent CMA testing, which identified one case of isochromosome X [46,X,i(Xq)] and two occurrences of pathogenic CNVs, specifically one duplication at 16p13.11 and one deletion at 7q11.22. Among the cases that yielded negative results from CMA, 45 proceeded to trio ES. Notably, two disease-causing variants, c.796-1G > A in PSMD12 and c.11707 C > T (p.Gln3903*) in KMT2D, were detected in each case. CONCLUSION: The diagnostic yields of 3.2% for CNVs and 4.4% for monogenic conditions suggest that genetic investigation may be warranted for pregnancies complicated by HSK.