As a child, I was always conscious of my mother lingering at the bedroom door, watching my chest rise and fall as I rested. Now, as I fall asleep, I too am tormented by my breath. Every wheeze and constriction fills me with dread, making the passage of deep breaths even harder. Some days I am too exhausted having lived to pay attention; I am grateful that I still have many such days. Sometimes as I lull myself to sleep I say a prayer for my genes: that the vibrant words they gave are never muted, and that my lethal lungs are soon mended.

My Irish Grandma Lizzie biked through British checkpoints with a sassy wink ready for the unsuspecting officers, who never knew she was smuggling artillery in her billowing skirts. As a young girl, I had no appreciation of the Troubles: her stories passed through my childhood afternoons like steam off the plate of settling biscuits, as I concentrated only on the milk swirling in my teacup.

Years later, I recalled threads of Grandma's tales, finally giving them due awe. I wondered what comparable mission I could stake out, what would be my territorial struggle. One college summer, as I read about the first gene therapy for cystic fibrosis, I knew. I felt more somber than elated, the promise of discovery discounted by a fear of disappointment. Still, the report led me to consider the potential and peril of hope in the face of genetic assault.

The generations could not have known that the double helix they bound for their offspring would be so duplicitous, that a gifted girl would be doomed to die of cystic fibrosis. But they also could not have predicted that battalions of scientists would lay siege to God's mind, fighting to change human fate. While civilians may remain complacent about the outcome, people are now fighting skirmishes all along the frontier, struggling with deficient genes, trusting that their healthful bounty will be restored.

I set out to document this conflict in Ireland, where my own genes are rooted. As witness to the escalating battle, I saw that some will be wounded by friendly fire, as new knowledge incites calls to winnow the most defective individuals, and that others will be lost long before the cures announce a truce. As participant, I now know, after a year at the front, that it is my birthright to wage war on the genetic minefield, and to survive.

Every weekend the good Samaritans congregate in front of the Swan Center in Rathmines, Dublin. They collect for the scourge of the week, tacking stickers on the lapels of those who offer up £1 coins. "Thanks very much," they say, and go back to joggling their buckets, donations clanging at one another inside.

Weekends are assigned by national lottery for those social or physical ailments the government deems most needy. The most helpless victims, the least politically charged causes, reap the greatest success. Sometimes the garnerers are vehement, controversial, and desperate, like rape crisis volunteers. Others seem to be kids, enlisted by their mother, "You'll shake the bucket on Saturday. Sure you will." There is an ethic in Ireland about dropping those extra pence–it is universally done. No one inquires about the intricacies of the suffering wrought by a particular disease. They are just grateful it is not their cross to bear, regardless of their own trials.

Cystic fibrosis is lucky to have a weekend in Advent. As in America, the pre-Christmas fervor makes for a particularly vigorous surge of generosity. The CF Foundation sells thick red candles, admonishing passersby to "give the breath of life." The mode of promotion is ironic to CF sufferers, to whom flaming tapers on birthday cakes present an annual pulmonary function test. The act of lighting a candle, a prayer of hope, is sacred. And there is no greater time for hope in the community of families faced with cystic fibrosis.

When they found the gene in late 1989, the world had yet to understand that pinpointing chromosomal locale did not alone constitute a cure. "Ah, you'll be grand," was the optimism proclaimed to the young sufferers throughout the British Isles. But the discovery was a greater boon for a generation of unborns than for those in the twilight of the disease.

"Now you can send mass cards," Katherine said when he died. "He was gone and all I was left with was mass cards."

Each day Katherine sat bedside at Dublin's National Children's Hospital, telling six-year-old Conor he was special. She tore up the blessings her husband's family sent, perhaps resenting that God would come between her and her son prematurely; she rebelled against any religious intrusion and thought any visitation would terrify Conor. And when the priest finally came, he greeted her and quickly administered the sacrament of the sick, the euphemistic, modern term for last rites. He left promptly.

"That man was from the church, wasn't he?" Conor asked.

"Yes."

"I really am special."

In the ward, suffering children would disappear. The others were told that the missing patients weren't sick anymore, didn't need to be here any longer. Those that remained would wonder what they could do to meet this fortunate result. But as they attained veteran status, and while more cohorts faded, they became certain of the deception. Openly discussing the sad truth was not deemed therapeutic by the pediatric professionals.

Conor dreamed of normalcy. During transplant evaluation they asked him why he wanted a new set of lungs. "So I can blow like my sister." He was jealous of his sister being home to play. Until the very end he wanted to join her there. But Katherine knew she couldn't deal with nursing her sick child alone the whole time. And she had heard the stories from "down country" about not being able to get back into the hospital once you had left.

He wasn't afraid to die, it seemed. Conor refused more antibiotics; they started a morphine drip. He and his mother had promised to save each other seats in the afterlife, as if there was some question as to who would enter the great picture show first. "Kids don't know not to believe in heaven," Katherine said. Parents are bound to offer beliefs they don't share in themselves. "I felt like I was in a tug of war with Him over Conor–and he was a toy doll being pulled in two directions. Finally, I found the strength to let go." After his death, Katherine astonished Conor's sister with the image of him forever free of cough.

There had been no CF in their family's genetic line. But having suffered one death and a CF diagnosis in a second child, daughter Orlagh, they chose to guarantee the brand of children they would bear. Katherine couldn't get a referral in Ireland, but the Hospital for Sick Children in London told her that Belfast City Hospital in the North would provide prenatal testing and follow-up abortion for genetic defect–services not available in the Republic. In two pregnancies, tragic history pushed Katherine and her husband to cross the border surreptitiously for peace of mind, siphoning hundreds of hard-earned pounds that would never be reimbursed by national health insurance. They made the train direct from Dublin's Connolly Station to Belfast, sitting silently side by side, their marriage vows fraying as they screeched along the historically explosive tracks. The British forces who walked the train at the border, screening for malevolence, provided an eerie parallel to the genetics detection and treatment taking place in Belfast City Hospital.

The three weeks between testing and results, as Katherine and her husband waited for the chromosomal workup, seemed an eternity. Both times the tests showed carriers–children who bore one copy of the gene but would never manifest symptoms. No one asks what they would've been done if another affected child had been uncovered; Katherine knows they couldn't have gambled on a CF child. And now their reproduction is complete. "We won't be having any more kids. That's been seen to."

Katherine released the tug-of-war rope before it ripped entirely. In relinquishing her son, all fighting efforts were for naught, the essence of defeat. She says she is not angry at God, but angry about Conor, and she no longer attends Mass. Still she laments the loss of her faith. "There are kids dying everywhere, and where else could you be closer to Conor than in Church?"

On Belfast's Falls Road I find myself in the sights of a soldier's gun. It seems safer to ask directions of the Royal Ulster Constabulary–two military lads mocking aim at me alongside a tank–than to enter any pub in this territory. I saunter over, try to employ my winsome inheritance. "The Royal Victoria Children's Hospital?" I ask in my plainly American voice, extending the sheet of hospital stationery that confirms my appointment with the pediatric pulmonology department. One of the camouflaged teens sizes me up top to bottom; the other scans me with his gun, from lethal heart to crippling kneecaps. Judging my coat too fitted to pack any plastic explosives, they direct me to the far side of the barbed fence three blocks away, and I continue on.

Michelle and Paul O'Brien marvel as their children engage in playful torment, their fingers and toes searching out vulnerable skin to pinch. Chloe is the terror, Martin the protector-just the demeanor for an older brother. Condemned to death, he wages valiantly on her behalf.

"Sixty-five horses," Martin exclaims, describing his affliction. "I've got sixty-five horses." He was diagnosed with cystic fibrosis barely two months after birth. He ate vast amounts, but the food ran though him; he failed to thrive. After the pediatrician's accusations of overreaction, the diagnosis came and the temper quickly changed. "Children die from this disease," Martin's parents were told. Paul's nephew had CF too, and at the age of 7 he was badly off. Whether due to privacy, ignorance or pride, the genetic susceptibility was never uttered to the family. Without knowing, the O'Briens lost the opportunity for carrier testing, and an occasion for prevention.

With existing technologies a fetus could be found to have the disease, and the parents would have the choice to abort. The O'Briens felt this was no option. They could not abort on a forecast of something they already had, a child with cystic fibrosis, but nor did they want to bring another CF child into the world. The timing of their dilemma was fortuitous. Scientists at London's Hammersmith Hospital had just begun an experimental study for pre-implantation diagnosis, a procedure which had been attempted unsuccessfully in the United States. Reports of the defeat were never published. So the British embryologists took to the task of fertilizing oocytes in vitro, screening pre-embryos for CF mutations, and implanting those that tested negative. No promises were made; only hope offered.

The timing had to be perfect for the eggs. First came the injections to stir ovulation. Then came the Tuesday morning harvest. The O'Briens arrived at Euston Station at 4 am and were at the hospital for egg retrieval by 6 am. Eleven eggs were removed from Michelle; six met fertilization the next day. From those they took the two best candidates, one "normal" and one "carrier," for Sunday re-implantation. Of the four other couples participating, the O'Briens were the only one whose in vitro fertilization attempt took. At twenty weeks they were informed there was nobody else left in the trial.

The doctors begged for amniocentesis. They had to know if their predictor was accurate, regardless of the procedure's risk of inducing a miscarriage. The O'Briens had retreated to the Midlands and were far enough from the lab to resist its entreaty. Science could wait the six months for satisfaction, they felt. Why take an additional risk when a detected mistake wouldn't push them to abort? "At nine weeks it's a baby," Paul reasoned, "not an egg with a view to maybe becoming a pregnancy."

Until the day Chloe was born, they never had any doubt that their child would be diseaseless. But the wait for her neonatal test was interminable. A blood sample was taken immediately and forwarded to the medical center. The results were supposed to return that afternoon, at 4 pm, then 6. Finally at 7:30 they were greeted by cork-popping nurses. A hospital leak sent the press aflurry. The scientists who performed the procedure learned of the blessed birth the next day, in the sensation-starved national dailies.

Debate flared in the papers and the O'Briens were pummeled with moral assaults. They met their attackers with absolute rage: "If they don't know, if they don't have a CF child of their own, how can they say whether its right or wrong? It's one thing to choose hair or eye color–it's another thing to choose to prevent suffering." They allowed one interview, with London's Daily Mail, at the request of the Hammersmith researchers. The £1,000 compensation covered their rail travel and lost work. "She was free," they say–the cost of her "production" absorbed by the research protocol. The results were published through the proper scholarly channels, eventually appearing in Science.

Martin traipses in: "My tummy hurts." An instant later he pivots and runs outside. He has learned to endure the pain, sensing the loss if he tarries in living. As a reward for the pound, pound of the twice-daily physiotherapy, Martin always gets a peck on the lips from his persecutor-cum-caregiver. Michelle and Paul are very clear in their affections. "It's not like we couldn't love a kid with CF because we love Martin and he has CF. It was just if there was something we could do to prevent it we'd try." And they look forward to the day when they can explain the wonder to Chloe by spreading the clippings they've saved across the kitchen table. In the meantime, Paul hails his baby girl. "You're famous," he says, and muffles her giggle in a hug.

"I left my rosary beads," Elizabeth had announced, bounding back into the mortuary where Stephen's body lay in state. Her parents had turned back, wondering if they should retrieve them for the six-year old. But before they could even ask themselves the question they stood watching her approach the corpse again. Helen and David had expected their daughter to react with grief, fear, confusion; she was too young to be so comfortable with death. But she had surprised them.

Stephen was one of Helen's closest friends during their battles with cystic fibrosis. He holidayed with the family the previous year. And Elizabeth wanted to go and see, to view the body taken and relieved of disease. David hesitated about initiating his daughter into the waking rite, but Helen knew she would think something awful about death if she were cloistered. "He's just asleep, Daddy," Elizabeth had said. "I mean he only looks like he's asleep. He's not going to hurt me or anything."

The family crossed the threshold to the casket. Elizabeth looked in. "Look he's wearing a t-shirt and he's got his new runners on. He's wearing his earring." Then they knelt in a prayer. At the funeral, weeping kin clutched Elizabeth. Family tears fell on her curly brass hair. She saw the suffering of CF more clearly than ever, not its endpoint for the victim but what it wrought on those bound to the sick. For she was bound. She confessed to her mother, "I'd love to say I hate CF, but I can't because you are." The understanding was born of the brusque clinical practice of naming patients by their diagnosis. "I'm not CF, I have CF," Helen explained. Helen had resolved not to burden her daughter with CF, but the disease touched everything about their lives: Elizabeth could not understand why her mother's friends died while her own peers did not.

For two years before Elizabeth was born, an unknown quantity had been killing Helen. She was shuttled from specialist to specialist, isle to isle. Her lungs bled; her body rejected food. Doctors, at a loss, injected her with her own infection to build resistance. Pneumonia ensued. She wed her handsome young caregiver, David, between ventures from her sickbed. They knew the bond would be short-lived. Helen said, "Yeah, that'll be grand. You'll get sympathy votes from all the good-looking girls. 'Look at you, you know, such a young widower."' No homemaking investments were made; they moved in with Helen's parents.

At 23, Helen finally learned her diagnosis. "I've got a touch of CF," she said, as if anyone could have just a smidgen. But the week's other revelation would make it impossible to treat her for at least six months. She had been told she was unable to conceive, been counseled on the benefits of childless coupledom. But now she was indeed pregnant, a circumstance that would either kill her or leave nothing to show for the ordeal. In Ireland she had no choice about course of action. However much David wanted Helen to be saved, the state could provide no reassurance. With abortion outlawed, she was forced to carry this potentially lethal entity.

The clinic at St. Vincent's Hospital in Dublin, the largest for adults with cystic fibrosis in the country, had never managed a pregnant CF. Their task was to keep Helen alive to delivery, in hopes that she would survive to proper treatment. Each day in the ward, she and David pored over literature. She was ostracized by the other sufferers for her curiosity. The sickest could not reconcile her fervor with their "why bother, you're going to die" attitude. Until months later, she could not grasp their hopelessness. By March, she'd seen two younger women die. And Helen wondered why she was so selfish to do this to her body, to carry a pregnancy and endanger potential convalescence. She was consumed with guilt, despite her lack of choice. Her doctor encouraged her to think of others. "The ones who never thought they could have children. For their sake."

No cheerful wallpapering, no stuffed teddies, no dangling mobiles filled Helen and David's home. They never prepared themselves to raise a child. Yet when Helen finally gave birth the nurses were reassuring. "The baby is fine–it's taken all the goodness from you," they said. Recovery began with commencement of antibiotic infusions. Helen and Elizabeth each got reprieves from their anticipated doom; David avoided the widower's fate and sorrow.

For a time, Helen got deeply involved in the CF community, serving on executive boards nationally and internationally. Phone calls, letters, weekend jaunts for her cause were all-consuming. Many friends who had been her initial supports died of CF, passed along to memory. Now Helen has retreated to tend her family. After ten years of marriage, the anecdote of the young widower has evolved: "To be honest, gosh, you're getting older now. It's not going to work so much on the sympathy for a widower after ten years compared to six months. And you have a daughter now, that's going to be a bit of a handicap." But humor does not always succeed, and there are moments when she wails to David, "I tricked you into marriage, you didn't know what you were taking on. You can get up and leave any time. I'm the one who has to live with CF."

When the home IV is hooked up, Elizabeth relishes minding her mother's drip. Helen wants to be strong for her daughter–she does not grimace or wince even when the nurse, searching for a vein for the line, misses the mark. When Elizabeth first faced a needle herself, at the pediatrician's for a routine immunization, she anticipated nothing, and she screamed when it pierced her arm. Protection had breached honesty. "You lied," she accused her mother. "You didn't tell me it hurt."

In February 1992, the Irish Government refused a thirteen-year-old rape victim passage to England for an abortion. Helen fumed in the kitchen: "Imagine them telling me what I can and cannot do." Elizabeth tried to mitigate the anger, telling her mother to ignore them. But when they went down to O'Connell Street in Dublin to watch the debate rage, the girl's zeal was apparent, even without any awareness of the issue's unique implications for her own birth. She clutched her mom's side as Helen waited in line to add her name to a petition. Elizabeth said she wanted to sign as well. "You can't. You're not old enough," her mother explained. Elizabeth protested, "But I want choices when I grow up."

I pace the Trinity College courtyard, releasing a cough with each moment of relative privacy among the bustling students at midterm, trying to avoid suspicion of contagion and the sidelong glares that accompany pariah status. Biking in the icy February drizzle has left me with a wrenching lung infection that even a pint of Guinness can't dull. When my congestion calms for a moment, I enter the Student Union to ring up the family I am slated to interview that evening. "Unable to make it out there today," I sputter, inventing an excuse. "Very sorry . . . next Thursday? Brilliant! See you then."

In return for their tales, I owe my families a depiction of health. Disease is my entree to their experience, as our common burden relieves them of tedious explanation. But hope is my currency: what I offer in exchange for their help. An ill visitor seeking confidence is more than an intrusive guest, she is a specter of future plague–evidence of the disease in me could doom their child. It is hard to convince young parents of the uncontainable clinical continuum, that some will die tragically young and others will survive long into adulthood. Given few predictors, I cannot account for my mild course. I can only offer encouragement to balance vigilant care with relative normalcy for as many years as possible. And so with a final cough and a prayer on each family's doorstep, I bound into the next household, the next life.

"Would you like a biscuit?" Mrs. Smith offers, when I arrive the following week. "Thanks," I smile, taking a shortbread. "Now you have to take pills, do you not?" I reach into my pocket and roll my capsules into my palm. Four-year-old Lesley Ann crawls the kitchen counter, reaches for the plate of sweets. "Now you know you can't have that without an enzyme," her mother scolds. Lesley Ann and I arrange our pills on the counter to compare. Mine yellow and grey, hers white, their enzymatic composition different, but the goal the same–smooth digestion. The little girl won't take her meds whole; her mother prepares applesauce to mix with the contents of her broken capsules. With her watching, I put my pill in my mouth, let it linger on my tongue, then swallow with a chaser of milk. As soon as I finish, Lesley Ann takes up her dose. Her attitude earnest as she closes her eyes, she lets it slide down her throat. The pill swallowed whole, she glows with pride; her mother puts my example on a par with sorcery. All evening the camaraderie lasts, between the young and the old patients who each day take mirrored measures to live for a cure.

Gene therapy findings are plastered across the popular press. But the incremental developments–installation of altered cells in nasal lining and such–are hardly the replacement needed for my clogged lungs. The biggest corporate biotech pioneers have promised hundreds of millions of dollars in CF research investment, and my loved ones are excited at each announcement. Yet I cannot care, for I do not want dollars but decades. Between Lesley Ann and me there is a generation of young people. Those born now are raised to live; those born twenty years ago were raised to die. With the hope of recent years, hundreds of thousands teeter on the cusp, working to keep well long enough to see "the cure." Spirit and science appear in tense consort: one is fostered while waiting on the other.

We live in an era of contradiction: genetic technology pledges to prevent the birth of sick children and also vows to heal sick children so they can survive to give birth. Ultimately, we are all casualties of nature, and we will increasingly know the genetic flaw inciting our death. I am a newly discovered and endangered species: that which flourishes in a productive third decade, constantly aware of no guarantees from modern medicine. There is a certain curse in having such sure but limited influence over one's own survival. Even those closest to me do not know the immensity of the preoccupation. I can run and medicate and purge my lungs of congestion. But discouragement threatens to hold sway. In the face of creeping, irreparable lung damage, I wonder how well I need to be to make gene therapy worthwhile. If I don't survive to see the cure, will I be to blame?

These days I am often awake in the hours before sunrise. I wonder what future lives will inhabit my tiny studio apartment–who will read my copy of Gatsby, moderate debates on organ procurement, visit the hospice patient in the nursing home. And though I worry that I do not exist uniquely enough to make a tangible difference, I think enough of myself to believe the world will lose something without my verve. Disease has given me license to be outrageous and demanding; those who don't have the context for these characteristics cannot grasp me. I am discouraged by people who confer admiration on my most basic accomplishments; I seek supporters who never think I have done too much, who will push me further for as long as possible. I focus my spirit to outlast my withering body. Illness trumps the freedom to pick one's fights.

Like generations before me, I ponder my stunted legacy. Some say I am too young and vital to do so. But it is a soldier's preoccupation.