Medical Findings in Infants Prenatally Identified with Sex Chromosome Trisomy in Year One of Life.

Background And Objective: Sex chromosome trisomies (SCT), including XXY, XYY, and XXX syndromes, have been historically underdiagnosed. Noninvasive prenatal cell-free DNA screening has significantly increased identification of these conditions, leading to a need for pediatric care for a growing population of newborns with SCT. Our goal was to analyze and compare perinatal features, medical diagnoses, and physical features in infants with prenatal identification of SCT conditions through the first year of life.

Methods: The eXtraordinarY Babies Study is an ongoing, prospective natural history study of prenatally identified children with SCT conducted by interdisciplinary teams in Colorado and Delaware. Participants were enrolled prior to 12 months of age and had pregnancy, birth, medical histories, and physical exams completed by board-certified pediatricians at 2, 6, and/or 12-month visits. Descriptive statistics were followed by comparisons between SCT groups using t-tests or ANOVA, Fisher exact, and correlations between medical features with alpha of 0.05. Relative risks were calculated compared to general population rates.

Results: 327 infants were included in the analysis (XXY=195, XXX=79, XYY=53). Major congenital anomalies were rare (1.7%). Relative risk compared to general population was elevated for breastfeeding difficulties (51.7%;RR 2.7), positional torticollis (28.2%;RR 7.2), eczema (48.0%;RR 3.5), food allergies (19.3%;RR 2.4), constipation requiring intervention (33.9%;RR 7.6), small cardiac septal defects (7.7%;RR 17.2), and structural renal abnormalities (4.4%;RR 9.7). Inpatient hospitalization was required for 12.4%, with 59.5% of hospitalizations attributable to respiratory infections.

Discussion: These findings of medical conditions with a higher prevalence can inform anticipatory guidance and medical management for pediatricians caring for infants with SCT.

Article Summary: Medical findings in largest cohort of prenatally identified infants with XXY, Trisomy X, and XYY from birth to 12 months and implications for pediatric care. One in ∼500 individuals have an extra X or Y chromosome, or sex chromosome trisomy (SCT). Prenatal screening is now routinely identifying SCT, however there are few studies to guide perinatal and infant care for these individuals. This prospective observational study presents medical features for 327 infants with prenatally identified SCT from birth through the first year of life. Results identify where proactive screenings and/or interventions may be warranted for infants with SCT.