Non-invasive prenatal testing for autosomal recessive disorders: A new promising approach

Abstract

Background: In pregnant women at risk of autosomal recessive (AR) disorders, prenatal diagnosis of AR disorders primarily involves invasive procedures, such as chorionic villus sampling and amniocentesis. Methods: We collected blood samples from four pregnant women in their first trimester who presented a risk of having a child with an AR disorder. Cell-free DNA (cfDNA) was extracted, amplified, and double-purified to reduce maternal DNA interference. Additionally, whole-genome amplification was performed for traces of residual purified cfDNA for utilization in subsequent applications. Results: Based on our findings, we detected the fetal status with the family corresponding different genes, i.e., LZTR1, DVL2, HBB, RNASEH2B, and MYO7A, as homozygous affected, wild-type, and heterozygous carriers, respectively. Results were subsequently confirmed by prenatal amniocentesis. The results of AmpFLSTR™ Identifiler™ presented a distinct profile from the corresponding mother profile, thereby corroborating the result reflecting the genetic material of the fetus. Conclusion: Herein, we detected AR disease mutations in the first trimester of pregnancy while surmounting limitations associated with maternal genetic material interference. Importantly, such detection strategies would allow the screening of pregnant women for common AR diseases, especially in highly consanguineous marriage populations. This technique would open avenues for the early detection and prevention of recessive diseases among the population.

Keywords: AR; Single gene; autosomal recessive; fetal DNA; non-invasive prenatal testing for monogenic disorders (NIPTM); whole-genome amplification.

FIGURE 1

Findings of case 1. (A) Sanger results for LZTR1 gene for mother and WGA product of cffDNA. (B) Sanger results for DVL2 gene for mother and WGA product of cffDNA. (C,D) Karyomaps comparison for LZTR1 and DVL2, respectively. (E) AmpFLSTR™ Identifiler™ Plus kit results for the mother and WGA product of cffDNA to detect maternal interference. (F) Ion reporter genome viewer for the WGA product of the cffDNA showing the high risk of trisomy 21 in the male fetus. cffDNA, cell-free fetal DNA; WGA, Whole-genome amplification.

FIGURE 2

Findings of case 2. (A) Sanger results for HBB gene for mother and WGA product of cffDNA. (B) Karyomaps comparison for HBB, gene between the mother and WGA product of cffDNA to detect the paternal allele and exclude ADO probability. (C) AmpFLSTR™ Identifiler™ Plus kit results for the mother and WGA product of cffDNA to detect maternal interference. ADO, allele dropout; cffDNA, cell-free fetal DNA; WGA, Whole-genome amplification.

FIGURE 3

Case 3 and case 4 findings. (A) Sanger results for RNASEH2B, and MYOA7A genes respectively, for the mothers and WGA products of cffDNA. (B) AmpFLSTR™ Identifiler™ Plus kit results for the mothers and WGA product of cffDNA to detect maternal interference.