Discrepancy in Fetal Sex Assignment Between Cell Free Fetal DNA and Ultrasound

PERINATAL/NEONATAL CASE PRESENTATION Discrepancy in fetal sex assignment between cell free fetal DNA and ultrasound

JI Iruretagoyena1, M Grady2 and D Shah1

Noninvasive prenatal testing utilizing free fetal DNA is commonly used in pregnancy to screen for trisomy 13, 18, 21 and also fetal sex aneuploidy. We report on two cases of discrepancy between phenotypic and genotypic sex and potential medical implications. In our first case, a patient with known male gender via cell free fetal DNA (cffDNA) testing had an ultrasound at 18 weeks’ gestation, which identified Dandy–Walker malformation and female-appearing ambiguous genitalia. As Dandy–Walker malformation could not be considered isolated in the presence of ambiguous genitalia, this finding allowed for more complete counseling of the parents as well as extensive genetic workup. Our second case involved a fetus with intrauterine growth restriction diagnosed by ultrasound and normal-appearing female genitalia. After birth, adrenal insufficiency was diagnosed and chromosome analysis identified normal male chromosomes. These two cases showed that fetal sex determination by cffDNA can be used as a tool for earlier identification of affected pregnancies, allowing for parental decision-making, genetic testing and earlier intervention.

Journal of Perinatology (2015) 35, 229–230; doi:10.1038/jp.2014.231

CASE declined. Serial ultrasounds were done until 30 weeks' gestation Patient A is a 32-year-old G2 P1 at 18 weeks’ gestation with an when reversed flow was seen in the umbilical artery. She delivered uncomplicated medical/surgical and obstetrical history. She had a normal-appearing baby girl weighing 1044 g with Apgars of 1, 6 an increased risk for trisomy 21 by first trimester screen at and 9. The early newborn course was complicated by respiratory 13 weeks’ gestation. After reviewing testing options, the patient distress syndrome and hyperbilirubinemia. Dysmorphic facial elected to have a cell free fetal DNA (cffDNA) test via the features and ambiguous genitalia were noted on physical exams, MaterniT21 test performed by Sequenom. The result showed the with labial enlargement, bilateral inguinal hernias, prominent expected amount of DNA from chromosomes 21, 18 and 13 and clitoral hooding and obscured vaginal introitus. Shortly after the presence of a Y chromosome, consistent with a male fetus. birth, she developed hypotension, hypoglycemia and worsening She then had a fetal anatomic survey during the second trimester respiratory distress. Adrenocorticotropic hormone levels were − 1 that showed the fetus to be affected by a Dandy–Walker elevated. Testosterone was 65 ng dl . After beta-human malformation and female-appearing ambiguous genitalia. Amnio- chorionic gonadotropin administration, testosterone rose to − 1 − 1 tic fluid was sent for karyotype and Smith–Lemli–Opitz syndrome 300 ng dl and dehydrotestosterone to 500 ng ml . Antimuller- − 1 (SLOS) test. SLOS is an autosomal recessive disorder of cholesterol ian hormone was 30 ng ml . After delivery, chromosomal metabolism that causes ambiguous genitalia. Karyotype showed microarray showed no evidence of deletions or duplications and mosaicism with four cells 46,XY and 10 cells 46,XY,add17p XY sex chromosomes. Fluorescent in situ hybridization for (additional genetic material attached to chromosome 17). SLOS sex reversal Y was positive confirming male gender. Magnetic testing was normal as well as both parents’ karyotypes. Fetal resonance imaging showed no uterus, no gonads present in the microarray was done to find the origin of the additional genetic pelvis and no suprarenal tissue. A male urethra with erectile tissue material in chromosome 17 and it showed a 30.54 MB duplication was found. Smith–Lemli–Opitz and NR5A1/NR0b1(DAX1) sequen- of the X chromosome as the additional piece on chromosome 17. cing and deletion/duplication studies were normal. This region contains 224 genes, but no imprinting region, likely The infant expired due to multiple respiratory and metabolic resulting in the overexpression of many of these genes. The complications. Autopsy confirmed the diagnosis of 46,XY sexual pregnancy was terminated due to these findings. disorder with bilateral gonadal dysgenesis, absence of uterus and Patient B is a 29-year-old G2P1 with an uncomplicated obste- gonads, presence of vasa deferentia bilaterally, vaginal opening trical history. She suffered from Crohn’s disease. She declined without clitoris and bilateral inguinal hernias. Unilateral suprarenal aneuploidy screening, and a fetal anatomic survey at 20 weeks’ agenesis and hypoplasia was found in the contralateral side. gestation showed a female fetus with no structural abnormalities. At 24 weeks’ gestation, the fetus was found to have intrauterine growth restriction with growth at the 3rd percentile. Although no DISCUSSION other structural abnormalities were identified, the patient was Since 2011, cffDNA analysis from maternal serum has been offered cffDNA and amniocentesis because of the association of commercially available for detection of chromosomal aneuploidy.1 growth restriction and chromosome abnormalties, but she Fetal DNA fraction can be detected as early as 4 weeks’ gestation

1Maternal Fetal Medicine Division, Department of Obstetrics and Gynecology, University of Wisconsin, Madison, WI, USA and 2Meriter Hospital, Madison, WI, USA. Correspondence: Dr JI Iruretagoyena, Maternal Fetal Medicine Division, Department of Obstetrics and Gynecology, University of Wisconsin, 1010 Mound Street, 4th Floor, Madison, WI 53715-1532, USA. E-mail: [email protected] Received 27 October 2014; accepted 24 November 2014 Discrepancy in fetal sex assignment between DNA and ultrasound JI Iruretagoyena et al 230 but a fraction superior as 6% is almost always present after women (for congenital adrenal hyperplasia carriers). In the cases 10 weeks’ gestation.2 Theoveralldetectionrateisveryhighfor presented in this article, the knowledge of the fetal sex prenatally trisomy 21, 18, 13 and the presence of a Y chromosome.3,4 More changed or would have changed dramatically the outcomes of specifically, the test detects more than 99% of trisomy 21, 98% of these pregnancies. trisomy 18 and 89% of trisomy 13 cases, with false-positive rates of As fetal free DNA becomes more commonly used not only in about 0.1, 0.1 and 0.4%, respectively.5 Fetal sex determination can high-risk pregnancies but also in low-risk pregnancies,5 clinical be carried out reliably from 7 weeks’ gestation using real-time situations as the ones presented would become more frequent quantitative PCR (RT-qPCR) to identify the presence or absence of Y and a new paradigm would need to be established both for 6 chromosome-specific sequences in the maternal plasma. The prenatally diagnosed ambiguous genitalia as well as discrepancy overall average sensitivity of using cffDNA to determine fetal sex in fetal sex between free fetal DNA and ultrasound. Chitty et al.10 7 is 96.6% and the overall specificity is 98.9%. It is estimated that published a review of cases with ambiguous genitalia, some with cffDNA gender identification is incorrect in about 1 in every 200 other ultrasound abnormalities as well as discrepancy between cases tested. phenotype and genotype and propose management strategies. In this paper, we present two cases of ambiguous genitalia/ cffDNA for fetal sex determination is done routinely in many discrepant fetal sex in which cffDNA assessment of fetal sex affected countries showing it to be reliable11 and cost effective12 when fi the way these pregnancies were managed. In the rst case, offered from 7 weeks’ gestation.13 Although cffDNA is approved awareness of fetal gender by ccfDNA allowed for better counseling only as a screening test due to the presence of both false positives of the parents and testing of the pregnancy. Ultimately, a duplication and negatives requiring follow-up with a definite diagnostic test1 fi of the X chromosome identi ed by microarray allowed us to inform (amniocentesis or chorionic villus sampling), many women accept the parents of the likely poor prognosis and the low recurrence risk in this test as a finaloneandwouldnotproceedwithadiagnostictest future pregnancies. Both cases had a normal complement of sex even when discrepancies occur as described in this report. Neonates chromosomes but were discrepant for the observed ultrasound with discordant gender would benefit the most of early focused phenotype. In the first case presented, the fetal sex was known diagnostic investigations shortly after birth. Overall if properly before the fetal anatomic survey. When ambiguous genitalia were counseled, the patient and future neonate would benefit tremen- encountered, the knowledge of the fetal sex helped in counseling dously of the suspicion of an abnormality allowing for further the parents and most importantly guiding the approach to investigation either prenatally or in the immediate postnatal period. investigate the potential causes of the ambiguous genitalia. In the second case, assumption was that the baby was female on the basis of the ultrasound findings and a normal physical exam in CONFLICT OF INTEREST the neonatal period. After a significant delay, the presence of The authors declare no conflict of interest. hypotension and electrolytes abnormalities led to a diagnosis of suspected adrenal insufficiency. Once chromosome analysis revealed an apparently normal male karyotype of 46,XY, further REFERENCES testing was initiated. 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