Very few cases of mosaic trisomy 13 combined with a monosomy X have been reported. It can be assumed that most likely the zygote was 47,XX,+13 and 2 chromosomes (13 and X) were lost simultaneously during an early postzygotic division. Here, we reported a 3-year-old girl with mosaicism of trisomy 13 and monosomy X. The child had a short neck, hypertelorism, depressed nasal ridge, epicanthal fold, mid-facial hypoplasia, thin upper lip, long philtrum, ear anomalies, postaxial polydactyly, atrial septal defect, hydronephrosis, and sensorineural hearing loss. Her weight and length were consistently below the fifth centile. She demonstrated global developmental delay when evaluated at 10 and 16 months. The range of developmental quotients (DQs) was from 0.6 to 1.1; the personal-social part was the best, and gross motor development was the worst. When evaluated at 31 months, the DQs of motor development were from 0.52 to 0.69, the object manipulation subscale was 0.52, the visual-motor integration subscale was 0.59 and the mental DQ was 0.52. Her social-behavior part was the best, language was the worst and the DQs had dropped with growth.
Conclusion: This is a case report of global development in a girl with mosaicism of trisomy 13 and monosomy X. The majority of physical anomalies observed tend to be mild and non-life threatening. Her DQs dropped with growth, and the language and mental development were significantly delayed after 30 months.