Sex discordance between cell-free fetal DNA and mid-trimester ultrasound: a modern conundrum

Prenatal Findings in Postnatal Cases of Disorders of Sex Development: Experience from a Tertiary-Specialized Center in Brazil

INTRODUCTION AND OBJECTIVE

Prenatal suspicion of disorders/differences of sex development (DSDs) is a relatively new phenomenon. The aim of this study was to review the prenatal findings of DSD cases postnatally diagnosed in our tertiary referral center.

METHODS

We evaluated 57 DSD cases with sex ambiguity who had undergone prenatal ultrasound with phenotypic sex assessment and/or cell-free fetal DNA (cffDNA) for genotypic sex assessment.

RESULTS

Prenatal cffDNA had been performed in 32 cases, being positive (suggestive of male genotypic sex) in 26 and negative (suggestive of female genotypic sex) in 6. Five with cffDNA negative had a prenatal ultrasound indicating female external genitalia, in turn, in those with cffDNA positive, only two had a prenatal ultrasound indicating male external genitalia. Our postnatal data showed that when external genitalia were female or poorly virilized, prenatal ultrasound indicated female sex, but in cases of higher degree of virilization, ultrasound showed similar rates of male, female, or undetermined sex. Regarding the karyotype, our data showed those with XY karyotype had positive cffDNA, those with XX karyotype had negative cffDNA, and all five with sex chromosome anomalies had positive cffDNA because they were 45,X/46,XY. We suggested an algorithm to investigate these cases during gestation, including evaluation of uterus, fetal growth, and malformations.

CONCLUSION

We suggest that the parents should be counseled prenatally by a dedicated multidisciplinary team with experience in DSD management and evaluated as soon as possible after birth.

Navigation of Prenatal Care With Sex Discordance Between Cell-free DNA and Ultrasound Findings

The utilization of cell-free DNA (cfDNA) screening has expanded rapidly across the age spectrum of pregnant persons. With cfDNA's widespread adoption, genetic fetal sex is now often known before a phenotypic assessment on anatomic survey. CfDNA detects sex discordance in 1/1500 to 2000 pregnancies. Upon detection of sex discordance, lab error or other factors should first be assessed. Once other causes have been ruled out, this may indicate an underlying disorder/difference in sex development. A multidisciplinary team should coordinate diagnosis, treatment, and support for the family. This review discusses the diagnostic workup, emphasizing the multidisciplinary counseling and management of disorder/differences in sex development.

Discordance in chromosomal and self-reported sex in the UK Biobank: Implications for transgender- and intersex-inclusive data collection

There is growing need to distinguish between sex and gender. While sex is assigned at birth, gender is socially constructed and may not correspond to one's assigned sex. However, in most research studies, sex or gender is assessed in isolation or the terms are used interchangeably, which has implications for research accuracy and inclusivity. We used data from the UK Biobank to quantify the prevalence of disagreement between chromosomal and self-reported sex and identify potential reasons for discordance. Among approximately 200 individuals with sex discordance, 71% of discordances were potentially explained by the presence of intersex traits or transgender identity. The findings indicate that when describing sex- and/or gender-specific differences in health, researchers may be limited in their ability to draw conclusions regarding specific sex and/or gender health information.

Fetal Genotype-Phenotype Sex Discordance: A Case of 5-Alpha-Reductase Deficiency

OBJECTIVE

To describe the prenatal and postnatal diagnostic workup leading to the diagnosis of 5-alpha-reductase type 2 deficiency (5AR2D) in a case of 46,XY disorder of sex development (DSD).

CASE REPORT

A first-trimester noninvasive prenatal test (NIPT) on maternal blood revealed a male fetus with a low risk of aneuploidy. However, a female fetus was identified at the second-trimester scan. A repeat sample revealed similar results and ruled out the possibility of both a sample swap or a vanishing twin. At birth, phenotypically female external genitalia were evident, with testes noted in the labioscrotal area. Neonatal blood confirmed a 46,XY complement and a 46,XY DSD genetic panel revealed a 5AR2D.

CONCLUSION

Our case and others described in the literature demonstrate that fetal sex discordance detected by a combination of NIPT and subsequent ultrasound examination can be associated with several biological conditions, with DSD being the most significant.

Prenatal diagnosis of a 46,XY karyotype female fetus with an SRY-associated gonadal dysgenesis, conceived through an intracytoplasmic sperm injection: a case report

Background

Permanent progression of paternal age and development of reproductive medicine lead to increase in number of children conceived with assisted reproductive techniques (ART). Although it is uncertain if ARTs have direct influence on offspring health, advanced paternal age, associated comorbidities and reduced fertility possess significant risks of genetic disorders to the offspring.

With a broad implementation of a non-invasive prenatal testing (NIPT), more cases of genetic disorders, including sex discordance are revealed. Among biological causes of sex discordance are disorders of sexual development, majority of which are associated with the SRY gene.

Case presentation

We report a case of a non-invasive prenatal testing and ultrasound sex discordance in a 46,XY karyotype female fetus with an SRY pathogenic variant, who was conceived through an intracytoplasmic sperm injection (ICSI) due to severe oligozoospermia of the father.

Advanced mean age of ICSI patients is associated with risk of de novo mutations and monogenic disorders in the offspring. Additionally, ICSI patients have higher risk to harbour infertility-predisposing mutations, including mutations in the SRY gene. These familial and de novo genetic factors predispose ICSI-conceived children to congenital malformations and might negatively affect reproductive health of ICSI-patients’ offspring.

Conclusions

Oligozoospermic patients planning assisted reproduction are warranted to undergo genetic counselling and testing for possible inherited and mosaic mutations, and risk factors for de novo mutations.