Omicron’s mutation occurred on set, where nearly every life-form is genetically identical to one another.
The Penn Pathology and Genomics Lab developed the variation from a normal chemical group — reductase 1. (The first name is in reference to from anagram of “OMcit” “omniphast” and “inoculates.”) The mutated version was then identified as a once-benign and otherwise functional gene.
In humans, strict adherence to the protocols laid out for parents who donate sperm or eggs is required in order to have the baby. In other words, human embryos do not develop beyond a few days if either or both parents did not donate sperm or eggs.
In Omicron’s case, a first-degree aunt contributed sperm, and a first-degree uncle donated egg. However, according to the father’s medical records, the sperm donation was made while he was a patient at Penn’s Geraldine R. Dodge Cancer Center in 2006. The test tube would not have been fertilized until 2008, which would have been when the baby was born.
The Omicron baby is unable to have any siblings, because their father had donated sperm once before, in 2004. “With two spontaneous spontaneous donors, you have a zero in the sibling group,” said one of the babies’ geneticists, Talie Hagner, who was not involved in the study.
The second baby’s doctors did not learn of his first donor’s donation until 2010, which would have been when they were doing a DNA survey to ascertain that neither of the parents was genetically predisposed to a particular illness.
Their explanation for not initially identifying the two donors was the strict protocols of gene donation, which dictates that parents who wish to contribute sperm or eggs to a fertility clinic have to obtain written consent, in addition to having undergone at least a couple of rounds of in vitro fertilization.
The embryos would then be taken to the fertility center, with one being transferred to the mother. During this part of the process, one of the babies would receive a procedure known as a hysterosalpingogram (HSG), which creates an ultrasound-based picture of the fetus.
The geneticists, though, have since found that Omicron’s father has the same form of hypoplastic left heart syndrome, as one of his two brothers, when he was still a child. “To me, it says that his body wasn’t able to accept this son,” Hagner said.
In cases in which the tissue was taken from an organ, “some experimental models have gotten similar forms” of placenta that had the Omicron baby’s form of hypoplastic left heart syndrome, she said.
But other forms of hypoplastic left heart syndrome can arise in live babies, as well as in infants born to a parent whose condition is benign, as was the case with the twins. While the Omicron twins’ medical history might not have been known in the past, evidence suggests that adverse events like infant death are infrequent in genetic testing of tissue banks.
Penn’s doctors did not attempt to contact the Omicron twins, the researchers said, because of their genetic purity. But they were alarmed by the potential adverse effects this mutation has on future studies.
Not everyone is convinced that the issue has been adequately taken care of by the sequencing of the twins’ DNA, which confirmed the presence of the mutation, although the author of one of the studies, Dr. Robert Bartholomew of the Bloomberg School of Public Health at Johns Hopkins University, stressed that “nobody can expect children to produce unaffected mitochondria all their lives.”
“Now, depending on the child’s health history, additional studies can be conducted to determine if this mutation may cause the variant syndrome that the two twins appear to have inherited from their father. If so, there will need to be ongoing screening for this disorder,” he wrote in an email.
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