• Courtesy of larissa barresi photography
• Sylvie and family

In January, our family of four celebrated our twin daughters' 10th birthday by bowling and playing air hockey at a loud, neon-infused entertainment center. That evening we ate take-out from our favorite local Thai restaurant and had a purple star-shaped cake with ice cream for dessert. I created a photo album for Uma and Sylvie with some of my favorite pictures of them over the last decade.

It all seemed so normal, yet for us it was particularly poignant. Sylvie has a fatal degenerative disorder, so the fact that we were joyfully celebrating both girls' birthdays was unexpected.

A year after my daughters were born, it became apparent that Sylvie was not hitting the typical developmental milestones and was actually losing ground. Within months, her abilities to sit, feed and entertain herself vanished. She became increasingly agitated and limp and started having mild seizures. It took almost another year — and a battery of tests, a muscle biopsy and a weekend in the intensive care unit — for the doctors to diagnose her with a rare condition known as Krabbe disease, which affects one in 100,000 children. It impairs the growth or development of the myelin sheath, the fatty covering that insulates nerve fibers, causing severe degeneration of mental and motor skills.

When we got the news, we were shocked — not at the confirmation of her delays but because we learned that her life would be very short. Eighty to 90 percent of children diagnosed with Krabbe don't live to their third birthday. Statistics are less reliable for those who survive past that point, since there are such a small number of cases. It would be realistic to think a child could live for four years after the date of diagnosis; an optimist could hope for seven and a half years. For our family, a birthday marking a decade of life was cause for celebration and reflection.

Author and public speaker Brené Brown suggests that parenting — even under the best of circumstances — is utter, excruciating vulnerability like most of us have never known before. In a culture that she describes as "allergic to vulnerability," Brown explores the crazy things parents will do to protect their children from the world. Yet, as I stand witness, when you have a child with a life-threatening illness, losing that child — your worst fear — is a daily reality. There is no protection.

Parents of children with unremitting health problems experience chronic stress, depression and unrelenting fatigue. Physical and social isolation, economic hardship, and lack of social services and support are all common for families such as mine. It's the kind of vulnerability neither my partner nor I had anticipated in deciding to become parents.

We never expected that our day-to-day lives would be filled with scheduling personal care assistants, navigating inadequate nursing services and advocating for full inclusion of children with disabilities in our schools. Most days we just fight like hell to get out of bed, take a deep breath and show up for whatever comes our way.

But this extreme vulnerability has an upside. Because we know we are living on borrowed time, we feel an intense sense of urgency. We know this disease will eventually wear Sylvie down. But I'll be damned if that means we're not going on vacations, visiting with friends, riding bikes, canoeing and enjoying what little pleasures we can afford. I understand why some parents of kids with special needs don't leave a three-mile radius of their homes. But I also have a healthy child who needs to be out in the world — and I want the world to see both of my kids.

When people first meet our nonverbal and nonmobile daughter, sitting in her wheelchair, her physical limitations are immediately apparent. Her differences often make people uncomfortable and sometimes fearful. They assume that Sylvie cannot see, hear or understand what those around her are saying, or that she is still a baby or toddler because she cannot walk or talk. Yet in her tiny, frail body, our daughter is a warrior. She laughs at our jokes and squeals when we get to a good part in a book or when a favorite song comes on during a movie. If you ask her to choose between vanilla or chocolate, she will always pick the latter with her eyes. Our daughter is more than just a disability and a rare disease.

Sylvie's disorder has offered our family, our friends and our larger community an opportunity to humbly think about life and death. We have had numerous moments when people have rallied to our defense: sitting with us as we process new medical information; playing secret Santa; delivering food to our family when Sylvie has been hospitalized; or organizing a fundraiser to get a cargo bike for family outings. We've learned a lot about the goodness of people and the power of community.

When my daughters were first born, friends gave us a rendition of a Maya Angelou poem, illustrated with neo-expressionist paintings by Jean-Michel Basquiat. It begins:

Shadows on the wall
Noises down the hall
Life doesn't frighten me at all
Bad dogs barking loud
Big ghosts in a cloud
Life doesn't frighten me at all

I read this book a lot when we were getting Sylvie's diagnosis, and somehow it made me feel just a little less vulnerable and more courageous. Its defiance of fear resonates with me — I see it in Sylvie, too.

With Krabbe, it feels as though we're walking a plank, and we keep getting moved to the back of the line so we can keep on living. As we watch other children we know succumb to this illness, I have tears in my eyes. But I, too, refuse to be frightened.