Pilot Screening of Cell-Free mtDNA in NIPT: Quality Control, Variant Calling, and Haplogroup Determination

Detecting mitochondrial mutations associated with aminoglycoside ototoxicity by noninvasive prenatal testing

OBJECTIVES

Numerous diseases and disorders are associated with mitochondrial DNA (mtDNA) mutations, among which m.1555A > G and m.1494C > T mutations in the 12 S ribosomal RNA gene contribute to aminoglycoside-induced and nonsyndromic hearing loss worldwide.

METHODS

A total of 76,842 qualified non-invasive prenatal (NIPT) samples were subjected to mtDNA mutation and haplogroup analysis.

RESULTS

We detected 181 m.1555A > G and m.1494C > T mutations, 151 of which were subsequently sequenced for full-length mitochondrial genome verification. The positive predictive values for the m.1555A > G and m.1494C > T mutations were 90.78% and 90.00%, respectively, a performance comparable to that attained with newborn hearing screening. Furthermore, mitochondrial haplogroup analysis revealed that the 12 S rRNA 1555A > G mutation was enriched in sub-haplotype D5[p = 0, OR = 4.6706(2.81-7.78)].

CONCLUSIONS

Our findings indicate that the non-invasive prenatal testing of cell-free DNA obtained from maternal plasma can successfully detect m.1555A > G and m.1494C > T mutations.

Cell-Free Fetal DNA and Non-Invasive Prenatal Diagnosis of Chromosomopathies and Pediatric Monogenic Diseases: A Critical Appraisal and Medicolegal Remarks

Cell-free fetal DNA (cffDNA) analysis is a non-invasive prenatal diagnostic test with a fundamental role for the screening of chromosomic or monogenic pathologies of the fetus. Its administration is performed by fetal DNA detection in the mother's blood from the fourth week of gestation. Given the great interest regarding its validation as a diagnostic tool, the authors have set out to undertake a critical appraisal based on a wide-ranging narrative review of 45 total studies centered around such techniques. Both chromosomopathies and monogenic diseases were taken into account and systematically discussed and elucidated. Not surprisingly, cell-free fetal DNA analysis for screening purposes is already rather well-established. At the same time, considerable interest in its diagnostic value has emerged from this literature review, which recommends the elaboration of appropriate validation studies, as well as a broad discourse, involving all stakeholders, to address the legal and ethical complexities that such techniques entail.