An uninformative NIPT as an early indicator of cri‐du‐chat due to a chromosomal 5;18 translocation—An atypical presentation of a rare cytogenetic phenomenon

We present a patient with cri‐du‐chat syndrome secondary to a rare cytogenetic mechanism. Our patient was the product of a dichorionic diamniotic twin pregnancy initially flagged with soft markers on ultrasound and uninformative single‐nucleotide polymorphism (SNP)‐based noninvasive prenatal testing (NIPT) for chromosome 18. Subsequent NIPT using proprietary‐targeted amplification methodology returned low risk for chromosomal aneuploidies 13, 18, and 21. Due to postnatal clinical findings, a clinical microarray and chromosomal karyotype confirmed cri‐du‐chat syndrome due to a de novo psu dic(5;18) (p15.2, p11.32). In this report we focus on these cytogenetic changes and discuss some of the current guidelines for prenatal microarray indications.