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Case Report: A male infant born at 37 weeks gestation. His mother was a 29-year-old, gravida 4 para 3 woman. During her pregnancy she was curious as to the gender of the fetus and requested a non-invasive prenatal test (NIPT) rather than fetal ultrasound. The NIPT returned with a karyotype of XXY. The male infant was born vaginally with a birth weight of 2670 grams. Apgar scores were 8 and 9 at one and five minutes respectively. He was admitted to the newborn intensive care unit secondary to respiratory distress. He had no obvious dysmorphic features. He had normal appearing male genitalia with testes descended bilaterally. Fluorescent in situ hybridization and blood chromosomes confirmed an XXY karyotype. He was discharged from the newborn intensive care unit with follow up by genetic counselors and close monitoring for developmental delays

Background: Klinefelter Syndrome (KS), a genetic disorder caused by the presence of supernumerary sex chromosomes. An additional X chromosome(s) and hypogonadism are the two defining features of KS. The excess of genes from the additional X chromosome drives the pathogenesis of the disease and distinguishing features of the affected individuals. The increase in the prevalence of prenatal testing has led to the earlier recognition of fetal chromosomal abnormalities. Early detection of KS through NIPT has given the family much needed information and allowing for early diagnosis and intervention, to promote the best outcome for the child. This case shows a patient that will benefit from the early diagnosis of a KS to implement early and timely interventions upon delivery and then later in the developing years. The neonate presented with no distinct, characteristic signs of KS, common in many individuals. Two findings, other than the NIPT results, weakly suggest any possible abnormality. Klinefelter neonates report mildly higher incidences of respiratory distress and low birth weight necessitating need for NICU admission. The underwhelming clinical presentation of the neonate shows that if NIPT wasn’t conducted, neither our patient nor his family would have known he was 47,XXY, until much later in life.

IMPLICATIONS: Timely hormonal intervention is possible for our patient because of NIPT. This demonstrates a need of a standard KS screen. With the technology of NIPT advancing and improving in its ability to detect a variety of other conditions outside of the traditional autosomal aneuploidy, it should be considered a technique for screening for clinically silent conditions, such as mild KS phonotypes.

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Klinefelter’s Syndrome: A fortuitously diagnosed by non-invasive prenatal testing

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