Prenatal genetic testing has advanced rapidly in the past decade. However, not all results, including variants, are well understood. We report the finding of a 2.5-Mb gene region quadruplication of Chromosome 17p13.3. This region is well characterized for the deletion leading to Miller-Dieker syndrome but has an unclear replication phenotype. Invasive testing performed after ultrasound abnormalities were seen revealed the quadruplication sequence as well as a short segment (850 kb) with x5 copy number variation. This region has previously been reported in a collection of duplications with shared phenotype; our quadruplication suggests similarities in phenotype. This raises the hypothesis of a potential spectrum or copy number variant-based phenotype.
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