Monosomy 18p with Unbalanced Translocation Between 13 and 18 Chromosomes: First Reported Case in Serbia

<b>Background</b>: Monosomy 18p is a chromosomal disorder resulting from the deletion of the short arm of chromosome 18. While a lot of cases result from the partial deletion of 18p, only a few reported cases are caused by the deletion of the whole short arm of chromosome 18 due to unbalanced translocations occurring between chromosomes 13 and 18 (13;18). 18p- monosomy presents with a variety of clinical manifestations, including facial dysmorphism, intellectual disability, and short stature, among others. <b>Case presentation</b>: Here, we report a case of a one-year-old girl with 18p- monosomy resulting from an unbalanced translocation between chromosomes 13 and 18 (45, XX, t(13;18) (q12:p11.2)). Our patient had facial dysmorphism and stunted growth. Additionally, she had hypotonia and required thyroxine supplementation from a young age. To our knowledge, this is the first case of astigmatism in a patient with this deletion and an unbalanced translocation between chromosomes 13 and 18. <b>Conclusions</b>: The present case demonstrates the phenotypic spectrum of a rare variant of monosomy 18 caused by an unbalanced whole-arm translocation between chromosomes 13 and 18. Our study emphasizes the significance of cytogenetic testing to diagnose this disease, which has been described only five times in the literature.