Researchers have managed to obtain the DNA blueprint of a fetus using only a father’s saliva sample and blood from the expecting mother. Obtaining the genomic information of a fetus before birth would enable thousands of genetic diseases to be detected, including recessive and dominant Mendelian disorders. In addition, because the procedure is noninvasive, it could provide a higher-resolution alternative to sampling of fluid from the uterus, which can detect a limited number of genetic disorders.
The breakthrough could give expecting parents an a new, and potentially controversial, decision to make as the embryo develops. Whereas now, parents have the option of determining what their new child’s gender will be, in the future they could learn about their child’s genetic profile. Those wary of the potential implications from this breakthrough cite the sci-film Gattaca, which presented a vision of the future of genetic discrimination based on embryo screenings.
“Although the non-invasive prediction of a fetal genome is now technically feasible, its interpretation—even for single-gene Mendelian disorders—will remain an enormous challenge,” explained Dr. Jay Shendure, associate professor of genome sciences at the University of Washington, in a statement. The research was led by Jacob Kitzman and Matthew Snyder, and was performed in the laboratory of Dr. Shendure.
The development, which was reported in the June 6 issue of Science Translational Medicine, relied on genome sequencing of two parents, genome-wide maternal haplotyping, and deep sequencing of maternal plasma DNA. The genomic sequence was determined at 18.5 weeks of gestation. The researchers repeated the procedure closer to the beginning of the pregnancy and monitored the precision of their genetic predictions using umbilical cord blood following birth.
The abstract from the study highlights the degree of accuracy of the sequencing:
Here, we combine genome sequencing of two parents, genome-wide maternal haplotyping, and deep sequencing of maternal plasma DNA to noninvasively determine the genome sequence of a human fetus at 18.5 weeks of gestation. Inheritance was predicted at 2.8 × 106 parental heterozygous sites with 98.1% accuracy. Furthermore, 39 of 44 de novo point mutations in the fetal genome were detected, albeit with limited specificity. Subsampling these data and analyzing a second family trio by the same approach indicate that parental haplotype blocks of ~300 kilo–base pairs combined with shallow sequencing of maternal plasma DNA is sufficient to substantially determine the inherited complement of a fetal genome. However, ultradeep sequencing of maternal plasma DNA is necessary for the practical detection of fetal de novo mutations genome-wide. Although technical and analytical challenges remain, we anticipate that noninvasive analysis of inherited variation and de novo mutations in fetal genomes will facilitate prenatal diagnosis of both recessive and dominant Mendelian disorders.
A video from CNN discusses this development:
Press release: Baby’s genome deciphered prenatally from parents’ lab tests…