P491: Mosaic double aneuploidy: A rare case of 45,X/47,XX,+18 mosaicism and review of the literature

folds, broad flat nasal tip, hypotonia, dental crowding, and flat feet.Medical complications include dextroscoliosis, hypotonia, osteoporosis, and astigmatism.At 14-years-old, height is 1.435m (< 1st percentile), although head circumference is 54.5 cm and weight is 61.2 kg, both within normal ranges.Diagnostic Workup: Karyotype analysis revealed 46,XX,dup(1)(q42q44). SNV microarray revealed microarray revealed a 19.24 Mb duplication of 1q32.2q42.13.Chromosomal analysis on both parents was normal, suggesting this variant was de novo or a result of gonadal mosaicism.Brain MRI revealed hypoplastic corpus callosum and hippocampus and an abnormal cingulate gyrus.