Clinical and molecular characterization of 18p deletion syndrome and a novel case with reproductive disorder

18p deletion syndrome (OMIM #146390) displays a variable clinical spectrum due to differences in deletion size, position, and penetrance. While several classical phenotypes have been linked to specific genomic regions, many genotype-phenotype correlations remain elusive. Here we present a 30-year-old female patient with the classical features of 18p deletion syndrome, along with reproductive endocrine abnormalities, including elevated prolactin levels and diminished ovarian reserve. Chromosomal microarray revealed a 13. 85 Mb deletion at 18p (arrGRCh3718p11. 32p11. 21 (136, 228₁3, 986, 303) x1). To better delineate the clinical and molecular cytogenetic findings associated with monosomy 18p and explore genotype–phenotype correlations, we also reviewed 41 reported cases (including the present case) with confirmed genomic deletions indexed in the PubMed database between 2010 and 2025. The results showed that terminal deletions were most common (66%), with interstitial deletions accounting for 32%. Among cases with breakpoint data, 71% had the proximal breakpoint at 18p11. 21, and 63% of deletions exceeded 10-Mb. Reverse phenotyping identified candidate intervals for multiple phenotypes: a 1. 2-Mb region (chr18: 1, 852, 498₃, 039, 186, hg19) was linked to white-matter abnormalities and ptosis, and a 5. 9-Mb region (chr18: 5, 416, 774₁1, 286, 578, hg19) was associated with white-matter abnormalities, ptosis, and autoimmune susceptibility. PIEZO2 and SMCHD1, located within the 5. 9 Mb and 1. 2 Mb regions respectively, are potential candidate genes for ptosis. PTPRM in 5. 9 Mb region is a potential candidate gene for causing autoimmune disorders. The genitourinary abnormalities presented here constitute a useful addition to the phenotypic spectrum of 18p deletion syndrome. However, their definitive inclusion in the syndrome’s clinical profile requires confirmation by future studies. These data expand the recognized clinical manifestations and refines potential candidate regions associated with key phenotypes, thereby providing a valuable resource for improved genetic counseling and future investigations into potential molecular targets.