CURRENT GENETIC COUNSELING PRACTICE FOLLOWING POSITIVE NON-INVASIVE PRENATAL TESTING FOR SEX CHROMOSOME ABNORMALITIES

The purpose of this study was to describe current prenatal and pediatric genetic counseling practice following a non-invasive prenatal testing (NIPT) result positive for a sex chromosome abnormality (SCA). The positive predictive value for SCA with NIPT is lower than seen for Trisomy 21 due to natural loss of the X chromosome from maternal cells during aging, confined placental mosaicism, and undiagnosed maternal sex chromosome abnormality. Except for 45,X, individuals with SCA usually have no ultrasound or postnatal findings. This makes follow-up for unresolved positive NIPT necessary; however, there are currently no clinical guidelines. This study used a prospective anonymous questionnaire to survey 176 prenatal and pediatric genetic counselors. Greater than 70% of pediatric respondents and \u3e80% of prenatal respondents were somewhat or extremely comfortable counseling patients about SCAs. However, prenatal respondents in the field for45,X (p88%) and anatomy ultrasound (~90%), but the percent consistently offering maternal karyotype (22-52%) and postnatal evaluation (28-87%) varied. Maternal karyotype was offered more often when NIPT was positive for 45,X or 47,XXX and patients had normal diagnostic testing (p72%) but the percent offering maternal karyotype (6-46%) varied widely. With the current inconsistencies, many newborns with undiagnosed SCAs who could benefit from growth hormone therapy, early intervention, and/or targeted surveillance may be missed. There is a need for professional guidelines to help improve clinical care for patients with NIPT results positive for SCAs