Discordant Embryonic Aneuploidy Testing and Prenatal Ultrasonography Prompting Androgen Insensitivity Syndrome Diagnosis

Complete Androgen Insensitivity Syndrome: A Rare Case of Prenatal Diagnosis

With the widespread uptake of noninvasive prenatal testing (NIPT), a larger cohort of women has access to fetal chromosomal sex, which increases the potential to identify prenatal sex discordance. The prenatal diagnosis of androgen insensitivity syndrome (AIS) is an incidental and rare finding. We wish to present the diagnosis of a prenatal index case after NIPT of cell-free fetal DNA and mismatch between fetal sex and ultrasound phenotype. In this particular case, the molecular analysis of the androgen receptor (AR) gene showed the presence of a pathogenic mutation, not previously reported, consistent with complete androgen insensitivity syndrome. Carrier testing for the mother revealed the presence of the same variant, confirming maternal hemizygous inheritance. Identification of the molecular basis of these genetic conditions enables the preimplantation or prenatal diagnosis in future pregnancies.

Fetal sex discordance

Fetal sex discordance is an entity that is becoming more frequent due to the expansion of the cfDNA for prenatal diagnosis. Its incidence can be estimated in 1/1500-2000 pregnancies, a frequency as high as that of some common chromosomopathies. The causes of this phenomenon are multiple and diverse, ranging from laboratory errors to important pathologies such as disorders of sexual differentiation. The management of a case of fetal sex discordance must be structured, starting with the review of the clinical history and the tests performed, and may require the performance of invasive tests to reach a diagnosis. Prevention through adequate pretest counseling and ultrasound confirmation can help to reduce its incidence.

[Genital abnormalities: Contextualization of a neglected area in prenatal diagnosis]

OBJECTIVE

To reflect on how the area of genital abnormalities has fallen behind in prenatal diagnosis.

METHODS

Based on the thesis that prenatal diagnosis of genital abnormalities has scarcely developed, a comparison with other areas of prenatal diagnosis and with its postnatal counterpart is presented; different explanations for this situation are examined; and a reflection is presented on ways to expand this field of knowledge.

CONCLUSIONS

Compared to other disciplines, prenatal diagnosis of genital abnormalities finds itself lagging behind in terms of diagnostic tools, management protocols and scientific literature. Potential causes include a perception of low prevalence and limited importance, or exploration challenges. Integration of current knowledge, together with the acquisition of the appropriate tools and translation to clinical medicine, would be a way to make this discipline stronger.

Prenatal detection and evaluation of differences of sex development

INTRODUCTION

Differences/disorders of sex development (DSD) can be detected at different ages, including prenatally. The recent implementation of prenatal genetic testing (including cell-free DNA) may affect the frequency and impact of prenatal diagnosis of DSD. Our aims were to (1) describe prenatal detection and evaluation of differences of sex development presenting to a multidisciplinary DSD clinic and (2) explore possible parental distress accompanying this evaluation.

MATERIALS AND METHODS

A retrospective chart review of mothers presenting prenatally, and patients presenting during infancy, to a multidisciplinary DSD clinic from 2013 to 2017 was conducted. Data extracted included demographics, final diagnoses, prenatal screening, prenatal evaluation, postnatal endocrine, genetic and radiologic testing, and clinician's notes on parent/patient distress.

RESULTS

Sixty-seven patients were identified; ten (15%) had prenatal detection of a suspected DSD. Of those, 4/10 were detected prenatally in the last study year alone. Within the prenatal group, 6/10 had cell-free DNA results discordant with ultrasound, 2/10 were detected by atypical genitalia on ultrasound, and 2/10 were detected through karyotyping performed for other indications. After birth, 3/10 patients were found to not have a DSD. Final diagnoses for the full study cohort are shown in the Summary Table, comparing prenatal versus postnatal presentation to our DSD clinic. Clinicians noted distress for most parents during the prenatal evaluation of a possible DSD, including one mother who reported suicidal thoughts.

DISCUSSION AND CONCLUSIONS

Prenatal suspicion of DSD can occur through discordant prenatal testing and has been observed at our clinic in recent years, in line with other recent studies. Contributing factors to these prenatal presentations could be increased referrals to the clinic, and increased use of non-invasive prenatal testing, which can lead to inaccurate or discordant sex identification. The prenatal suspicion of a potential DSD can be associated with parental distress, underscoring the need for adequate counseling for tests that determine fetal sex, including cell-free DNA.

Fetal sex discordance between noninvasive prenatal screening results and sonography: A single institution's experience and review of the literature

BACKGROUND

With the increasing availability of noninvasive prenatal screening (NIPS) and high-resolution ultrasound, more cases of sex discordance are being identified in routine clinical practice. This can be a source of much concern for families and clinicians. Knowledge about the limitations of NIPS and reasons for discordant results are critical for counseling parents.

AIMS

Here, we present three cases from a single tertiary care referral center. We also review the literature to address potential limitations of NIPS in correctly identifying fetal sex chromosomes.

MATERIALS AND METHODS

After Institutional Review Board approval, cases of discordant fetal sex were identified using ICD-9 and ICD-10 codes. In addition, departmental counseling database and cytogenetics laboratory logbooks were reviewed.

RESULTS

In our first case, a 37-year-old G4 P2012 underwent NIPS at 11 weeks gestation and Monosomy X (associated with Turner syndrome) was identified. Morphological sonographic assessment at 20 weeks gestation was consistent with a female fetus following an amniocentesis at 16 weeks that revealed normal 46, XX karyotype. During the third trimester, the patient was diagnosed with Stage IV invasive ductal carcinoma of the breast. Postnatal follow-up of the neonate was consistent with a phenotypic female. In the second case, a 22-year-old G2 P1001 obese female underwent NIPS at 14 weeks gestation and normal 46, XY karyotype was identified. Morphological sonographic assessment at 20 weeks was not consistent with a male fetus. The patient declined invasive testing. Postnatally, the karyotype was 46, XX and the neonate was phenotypically female. The reason for the discordant results was not identified. In the third case, a 25-year-old G1 P0 obese female underwent NIPS at 13 weeks gestation and normal 46, XY karyotype was identified. Morphological sonographic assessment at 20 weeks was indeterminate; however, follow-up at 24 weeks was consistent with a female fetus. The patient declined invasive prenatal testing. Postnatally, the karyotype was 46, XX, and the neonate was phenotypically female with uterus present on ultrasound. The reason for the discordant results was not identified.

DISCUSSION

Our cases demonstrate possible limitations of NIPS in correctly identifying sex chromosomes.

CONCLUSIONS

Providers and patients need to be aware of these limitations, and invasive diagnostic prenatal testing should be offered in cases of discordance between NIPS and sonographic sex assessment.

The importance of pre- and post-test counseling for prenatal cell-free DNA screening for common fetal aneuploidies

INTRODUCTION

Prenatal cell-free DNA screening for common fetal aneuploidies has rapidly changed the paradigm of prenatal care. Despite its advantages compared to conventional screening methods, its unexpectedly rapid implementation in clinical practice has generated several ethical and medical issues and misconceptions. Aggressive commercial marketing of cell-free DNA screening and media dissemination of misleading information have added confusion. Areas covered: This review provides an extensive update and will focus on the importance of pre-and post-test counseling for prenatal cell-free DNA screening not previously discussed extensively in the available literature. Additionally, we report cell-free DNA screening implementation in the largest obstetrical tertiary unit in Finland which is one of few countries that provides all prenatal screening methods free of charge for all women and has a very high uptake of first-trimester screening. This is not a systematical review, but rather a narrative overview which includes the most relevant and recent original publications and reviews covering this issue. Expert opinion: Despite being the most accurate method for screening of common fetal aneuploidies, the knowledge and counseling should be substantially improved. Cell-free DNA screening is not a replacement for diagnostic testing and its use in prenatal testing is complex and limited.

Discordant sex between fetal screening and postnatal phenotype requires evaluation

OBJECTIVE

Non-invasive prenatal screening (NIPS) utilizes circulating cell-free DNA (cfDNA) to screen for fetal genetic abnormalities. NIPS is the first widely-available prenatal screen to assess genotypic sex. Most pediatricians have limited familiarity with NIPS technology and potential etiologies of discordant results. Increased familiarity may provide diagnostic insight and improve clinical care.

STUDY DESIGN

We reviewed all patients with discordant genotypic fetal sex assessed by cfDNA and neonatal phenotypic sex referred to our medical center.

RESULT

Four infants with discordant cfDNA result and phenotypic sex were identified. Etiologies include vanishing twin syndrome, difference of sexual development, sex chromosome aneuploidy and maternal chimerism.

CONCLUSIONS

We present four cases illustrating potential etiologies of discordant cfDNA result and postnatal phenotypic sex. Unanticipated cfDNA results offer the perinatologist a unique opportunity for early diagnosis and targeted treatment of various conditions, many of which may not have otherwise been detected in the perinatal period.

Prenatal Diagnosis of Twin Fetuses with a Novel AR Gene Mutation in a Chinese Family of Complete Androgen Insensitivity Syndrome

INTRODUCTION AND AIMS

Androgen insensitivity syndrome (AIS) is an X-linked recessive genetic disorder caused by mutations in the androgen receptor (AR) gene. Only a few cases of AIS with AR gene mutations have been diagnosed prenatally. This study aimed to investigate the gene mutation in a Chinese complete androgen insensitivity syndrome family and perform prenatal diagnosis for twin fetuses.

CASE REPORT

We evaluated the AR gene of the child proband in a Chinese CAIS family, and detected a novel mutation c.3864T>C (p. Phe917Leu). Amniocentesis was performed when the mother presented to our hospital with a subsequent twin pregnancy. Mutation analysis revealed that both fetuses were hemizygous for this mutation. The aborted fetuses had typical female external genitalia and bilateral testes in abdomen.

CONCLUSION

The c.3864T>C AR novel mutation is responsible for complete androgen insensitivity syndrome, and its identification was subsequently used for a subsequent successful prenatal diagnosis.