Prenatal genetic testing and the light of mercy

With the advent of genetic carrier screening for parents looking to conceive, how should couples evaluate their options on the basis of the true and the good?

Photo by on Unsplash

The Gospel of John saturates our minds and hearts with the law of self-gift. The life-defining reality that the Son of God—out of his infinite mercy—gave up his body and poured out his blood is a model for each of us. It’s a command calling every last one of us to a life of radical self-emptying. It is precisely the key to unlocking the stunning beauty of Mackenzie Casella’s life.

Who is Mackenzie Casella?

Mackenzie Casella was born on March 11, 2017 in Sydney, Australia. Her parents, Rachael and Jonathan, described their daughter as “pure perfection.” The Casellas, both officers of the Sydney police force, had wanted to conceive as soon as they got married, and, to that end, spent the months before their marriage eating healthily and doing acupuncture, blood tests, and fertility checks.

They enjoyed 10 “blissful weeks” with Mackenzie before their world fell apart—before Mackenzie was diagnosed with spinal muscular atrophy (SMA) type 1, a degenerative neuromuscular disease that usually kills within two years after birth. The disease leads to poor head control, weakness of muscles of the chest wall, difficulty/inability to cough or breathe deeply, and weakness in arms and legs resulting in the failure to roll or sit. There was no effective treatment for the disease during Mackenzie’s short life.

Six months after her diagnosis, on October 18, 2017, Mackenzie came down with a cold. She struggled to breathe, and then stopped breathing altogether. Rachael and Jonny frantically called an ambulance as they helplessly watched the failure of Mackenzie’s small lungs and breathing muscles to clear the mucus caused by her cold. Three days later, when Mackenzie’s hemoglobin level revealed she was bleeding into her stomach; when doctors failed to stop the bleeding; when they referred to the ventilator as comfort care, Rachael and Jonny realized they had lost the battle for Mackenzie’s life.

Days later, on October 22, Mackenzie passed away at Sydney Children’s Hospital.

What is Mackenzie’s legacy?

It wasn’t until Mackenzie was diagnosed with SMA that Rachael and Jonny discovered each of them carry one copy of the SMA defective gene, SMN1. Because the other copy of the gene was functioning normally, neither Rachael nor Jonny suffered the symptoms of SMA. And, because they were never tested, neither of them realized they were both carriers for the same genetic disorder. Neither knew that, as a couple, they had: a one-in-four chance of passing on both copies of the SMA gene to their child, giving that child SMA; a two-in-four risk of passing a single copy of the bad gene to their child, making that child a carrier of SMA; and only a one-in-four chance of passing on two copies of the normal gene, so the child would neither be a carrier of, nor suffer from, SMA.

After Mackenzie died, the Casellas spearheaded a campaign to raise awareness of the importance of genetic carrier screening. They were determined to inform every couple in Australia of the simple facts about which they had been ignorant: many people are carriers of several recessive genetic conditions without ever knowing it. One in 40 people is a carrier for SMA. If you combine the levels of SMA with those of cystic fibrosis and Fragile X syndrome, one in 20 people carries one of these disorders—the same prevalence as Down syndrome. SMA is the number-one genetic killer in babies under two, and a simple blood or saliva test can detect the defective gene responsible for the condition.

The Casellas lobbied their legislators. They wrote to all 275 members of the Australian parliament and recounted Mackenzie’s life, her battle with SMA, and what could have been different if Rachael and Jonny had known they were genetic carriers for SMA. Eventually, the Casellas caught the attention of Greg Hunt, Australia’s Federal Health Minister. Rachael and Jonny had a face-to-face TV interview with him, and during the dialogue, Hunt announced Parliament’s decision to donate the single largest investment of the Medical Research Future Fund to what he dubbed “Mackenzie’s Mission.” Its goals: first, to offer free genetic carrier screening for more than 500 autosomal recessive genetic conditions to any Australian couple who would choose to be tested either before pregnancy or in early pregnancy; second, to raise awareness in the medical community and among prospective parents about the hidden risks of passing on recessive genetic conditions; third, to equip couples who have an increased risk of conceiving a child with a genetic disorder with the necessary knowledge “to make choices according to their own values”; fourth, to provide funding for research and genetic testing; and fifth, to eventually make IVF more accessible for couples who are carriers for genetic disorders.

Rachael and Jonny convinced government leaders to embrace their vision: a world where couples who are genetic carriers know it, and know what chances they have for passing the genetic condition on to their children. “With this information,” Rachael and Jonny said, “parents and doctors can make informed decisions.” For genetic disorders that are manageable, parents can better plan the post-natal life, play, and education of the child. If the parents know about the genetic disorder in advance, and if the disease can be cured or treated at birth, they can plan for a treatment as soon as the baby is born. But:

[i]n some cases, the disorders are so life threatening, painful and cruel that a parent may decide they don’t want their child to go through that so they can look at alternatives such as IVF to make sure their child is not born with that disorder.

How might the light of mercy transform “Mackenzie’s Mission”?

Aquinas defines mercy as an affect or an emotion. Affective mercy—based as it is in human nature’s vulnerability to suffering, on the knowledge that we are all subject to the same travails—enables one human being to be empathetic toward another who is in anguish. The closer we are to someone who is suffering, the greater the intensity in our affective mercy. Put simply: we regard a friend’s sorrows as our own, and we grieve over our relative’s troubles as if they were our own.

On the other hand, Aquinas explains effective mercy is not an emotion, but something we do: a positive action “for the good of another,” “to relieve the miseries or meet the needs” of a fellow human being. Of the three kinds of misery in life—suffering that acts against our natural desire to live; suffering that strikes suddenly, such as that caused by an accident; and misfortunes that strike an innocent, like Mackenzie, who doesn’t deserve them—the latter is the worst of all: the suffering that befalls someone who is pursuing the good and yet is overcome by a physical or moral evil.

Effective mercy follows from a virtue, from the good habit of relieving the misery of another. The authentic virtue of mercy has two characteristics: first, it is rooted in “right reason,” that is, in the truth about another’s suffering, and in the genuine good of the suffering person we are trying to help. Second, the virtue of mercy must go beyond the simple affect or feeling of mercy—beyond a mere sympathy for the miseries of another. It must actually be driven by “misericordia,” by having a “miserable heart,” by the practical drive to do something to relieve the anguish of others.

At first blush, Rachael and Jonny Casella certainly seem to display “misericordia,” a heartfelt desire to do something to relieve the angst of other couples who are carriers for genetic disorders. To aggressively lobby government to provide publicly subsidized carrier testing appears to be a genuine expression of empathy. Ostensibly, the Casellas are, first, acting out of their desire to support spouses who, before they get pregnant, both test positive for carrying a defective gene for some recessive genetic disorder and decide either to forgo parenthood, to adopt, or to access IVF.

Second, the Casellas are allegedly attempting to assist couples who are already pregnant, test positive for carrying the same genetic mutation, and discover they have conceived a baby who is either a carrier for, or who actually has, the genetic disorder. This knowledge presents the last couples with two possibilities: to take the baby to term and deal with the condition post-natallyor to abort the baby.

However, are these pre-conception and post-conception options for genetic carrier couples rooted in reason, namely, in the truth about the suffering of the couple or their child? Are they grounded in the genuine good of the couple and child? On the basis of the true and the good, let’s evaluate, in turn, each of the carrier couples’ pre-conception and post-conception alternatives.

Pre-conception option #1: Deciding not to have children

If a couple discovers they are carriers for a serious genetic condition, the decision to not have children is, in and of itself, not morally problematic. It’s neither against their good and their happiness nor against the redemptive truth of their difficult situation—having to forgo biological parenthood because of genetic predispositions.

However, certain provisos must be respected. First, the couple have to find some way to bring their love to perfection in giving life to other people—reaching out to the poor or elderly—or to other people’s children who either lack parents or stand in need of extra parental guidance and love. Second, they have to avoid biological parenthood in a moral way, that is, without directly suppressing their fertility through contraception or sterilization. By using a natural system to identify the fertile phase of their cycle, they can avoid a pregnancy in a manner that honors both the procreative and unitive dimensions of their marital sexual love.

Pre-conception option # 2: Adopting or helping to raise other people’s children

Again, adopting a child, taking a foster child into their home on a temporary basis, mentoring children who lack good parental direction, or helping to raise nieces and nephews who need extra attention and love are all acts to be lauded. They are self-gifting acts of mercy rooted in right reason. All things being equal, these examples of selfless love would bring a carrier couples’ love to perfection by giving life to other people’s children.

Pre-conception option #3: IVF

For the couple who discovers they are carriers for a serious genetic condition such as SMA, accessing IVF and preimplantation genetic diagnosis may appear to be a genuinely merciful choice. Until, that is, IVF, preimplantation genetic diagnosis, and the treatment of IVF embryos, are clearly understood.[1]

As the technical simulation of the procreative structure of the marital act, IVF sunders the link between procreation and the act of sexual love. Tragically, the in vitro technique robs human generation of the only context that makes the coming to be of a new human life human: the personal, sexual act of its parents’ self-giving love. Divorced from the interpersonal communion of spousal love, the fertilization of an embryonic human being in a petri dish becomes nothing more than a rational, productive action oriented to a goal. And the parents’ intention—to generate a child—fashions the child into a product, into the object of their producing or creating.

By submitting the embryos to preimplantation genetic diagnosis, physicians and parents manufacture the child according to their own image, their own genetic and developmental criteria. Those embryos that “pass” the genetic test are transferred to the mother’s uterus; those who fall short of the genetic yardstick are destroyed.

The couple utilizing IVF says to their child, in effect, “You live because and in the measure that we want you, in the measure you conform to our genetic specifications.” As the product of his parents’ will, the baby becomes a mere means, an instrument, for the satisfaction of their desire for children without genetic defects. There is no other way to put it: the parents use the child as an instrument to fulfill their desires.

For all these reasons, IVF parents make the life of their child depend on their desires, on their will and, ultimately, on their power. Such power sets the IVF parents over against their child, creating a relationship riddled by gross inequity. The child, after he is old enough to reflect on his beginnings, might also feel an inordinate obligation to measure up to his parents’ “expectations”; this sort of existential dependence would contradict his fundamental equality with his parents and all other human beings.

As such, the IVF parents’ conditional love for their child contradicts a principal demand of justice, the Golden Rule: the parents fail to accept their child in a manner they would want to be accepted. The will of IVF parents to produce a child technologically opposes reason precisely in its opposition to justice, a basic component of human rationality.

This is why the Church insists that the generation of a baby within the marital act provides the only way for parents to, first, accept their child and, second, to respect and recognize the child as someone “equal in personal dignity” to them (Donum Vitae, Part II, section B, chapter 4C). The marital act of love and union is the only reproductive context in which the parents can welcome and love their child unconditionally—as a gift—as someone whose mere existence is, already, per se, a good. And the parents’ unconditional love for their baby is the only way to accept their child justly, giving the child what is due him or her as a human person equal in dignity to every other person.

Post-conception option #1: Carry the baby to term

On May 24, 2019 the FDA gave approval to the pharmaceutical company Novartis for its gene therapy Zolgensma, capable of saving infants who, like Mackenzie, are born with SMA type 1. This one-time treatment uses trillions of viruses to insert a functional copy of the gene SMN1 into all the cells of a child with SMA type 1. Created by a team of scientists and clinicians at Nationwide Children’s Hospital, the treatment has produced stellar results. The demand for Zolgensma has increased, since states like Minnesota and Pennsylvania now include SMA in the panel of diseases for which babies are routinely checked. Unfortunately, the astronomical price of this treatment puts it out of reach for most. But Zolgensma’s success in clinical trials has created incentives for insurance coverage to bring the price within reach of normal family budgets.

The availability of this drug in the US to treat babies with SMA type 1 presents a new possibility for couples who are gestating a baby with this condition. It was not available to the Casellas in 2017, but now Australian couples should also be able to access this drug so that the diagnosis of SMA type 1 need not lead to inevitable loss of life.

But even if Zolgensma was not be available or not affordable, isn’t the decision to do what the Casellas did—namely, permit Mackenzie to live as long as possible—following the true gift of Mackenzie’s legacy? In the seven months and eleven days allotted her, Mackenzie offered her parents and everyone who knew her the essence of what it is to be person-as-gift. Our prayer should be that those faced with similar challenges learn to put the objective truth and goodness of what Mackenzie communicated into practice.

Post-conception option #2: Abort the baby

The tyranny of relativism rears its ugly head when the goal of Mackenzie’s Mission is to arm Australian parents with genetic knowledge so they can “make choices according to their own values.” Sadly, under the banner of moral relativism, the “values” of one Australian couple led them to decide to abort their baby diagnosed with SMA type 1. Their description of the abortion, shrouded in euphemisms, betrays the reality of what they were doing: “We now face having to medically interrupt the pregnancy this week, say goodbye to our baby, and turn back to IVF.”

The truth is that genuine mercy demands that the carrier parents’ choice for their SMA baby in utero be grounded in what is in full accord with reason, in what conforms to the full redemptive truth of the suffering of baby and couple, and in the genuine good—the intrinsic dignity—of the life of both baby and parents. This is, after all, the way Rachael Casella describes Mackenzie’s legacy:

I feel like I have been given a secret door, a short cut, to navigating the maze that is life. I wish I had developed this perspective without having…to go through this. But I choose to see this as a gift that Mackenzie gave me. She made me a better person, she changed my life. To forget my new perspective, and not act on it, would feel like I was dishonouring her life.

Only the “right reason” of authentic mercy will be able to actively transform Mackenzie’s Mission—together with all the choices that open up to genetic carrier couples as a result—into a mission that honors the person-as-gift legacy of Mackenzie Casella.


[1] I deal with the injustice of IVF in detail in “NaProTechnology: A Remedy for the Injustice of IVF,” Fellowship of Catholic Scholars, Numbers 3/4, Fall/Winter 2016.

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About Sister Renée Mirkes 20 Articles
Sister Renée Mirkes, OSF, PhD a member of the Franciscan Sisters of Christian Charity, directs the Center for NaProEthics, the ethics division of the Saint Paul VI Institute, Omaha, NE. She received her masters degree in moral theology from the University of St. Thomas, Houston, TX (1988) and her doctorate in theological ethics from Marquette University, Milwaukee, WI (1995).


  1. Thank you CWR and Ignatius Press for a good banquet of good , timely articles , this one above , on this Feast Day of St.Monica too , bringing to clarity , the Church’s teachings on dangers of in vitro fertilization , with the care of the Heart of a Mother .
    Sobering to read about the prevalence of genetic disorders .
    Interesting to see the mention of acupuntcure as one of the things the couple resorted to , to have a healthy pregnancy ; unsure if same too is in the same class like yoga, warned by exorcists to have potential for adverse effects .
    The Miraculous Medals , given for our times , with the truth and blessing related to the holy conception of our Blessed Mother – would it be that same has benefits that are hidden , with the potential to prevent many of the dangers in these realms !
    The devotion to Our Lady of America also related to same , possibly to counter the way many of the evils of our times are also from this realm in the country , exported to world over as well .
    Good to read about the techno remedy as well .
    O Mary , by thy holy and Immaculate conception , deliver us from evil .

  2. Dear Sister Renee Mirkes, my greatest respect and humble reverence for you and the gifts of Life of the Holy Spirit that you have shared in this amazing Spirit-filled article!!! I always strive to live in Truth, as Jesus is the Truth Himself and there’s no trace of Real Love without His Truth! Truth should always be first as Authentic Truth is the Very Guardian of True Love. God has made you one of those guardians and so should every and all Catholics be!!

    Our Holy Catholic Church needs to shed forever those hyper attractive, ego-worshipping, ultra popular, sinful impostors and counterfeits from Satan of every virtue and every pure, noble and holy thing that God has created. He affirms LIFE through Mary and Joseph keeping Jesus from the hatred and murder coming against Him. Like you say, they accepted Jesus-as-Gift even though even at His Birth suffering followed Him, with Innocents that had to die in his stead, so later Jesus could die in stead of you and me, and all humankind of all time.

    Today’s popularized “love and compassion” have no elements of Truth whatsoever, so they are false and, because they are false, they have to be pushed with the most agressive, nastiest, most intellectualized level of self-righteousness, accusation, shaming and falsely pontifical attitude, sometimes even using spiritual language and Bible quotes, worst of all by some Catholics, who believe they are “champions of love”. You are a True Champion of Truth and Love, Sister Renee, and with all due respect to your growth in the Lord Jesus, I pray and hope that all consecrated women follow your example, because you are a direct example and follower of Most Holy Mary’s example and her True Love, Mercy and Faithfulness faithful to her Son who is the Truth Himself!!!

  3. Late comment since I’m about a month behind on CWR:
    Outstanding analysis, sister!
    Keep writing.
    I will pray that God allow many people to read and understand your writing!

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