Rick Karl, left, and Bruce Steiger play with their daughter, Krystie. When Karl and Steiger decided to have a child, they hired a surrogate and used a donor egg. Krystie was born with Tay-Sachs. (Allen J. Schaben / Los Angeles Times)

The particulars of Alexandra Gammelgard's egg donations are a bit of a blur to her.

Between the ages 18 and 21, she donated to at least four infertile couples, using two, maybe three, agencies that paid her from $5,000 to $15,000 for each donation. She was trying to pay for her education at UC San Diego and didn't keep track of the details.

"The college years of your life go by so fast, and you do so many crazy, random things that it's hard to remember it all," Gammelgard, now 23, says.

She believes at least four children were conceived from her eggs, results she was proud of. In recent months, however, she got grim news: One has Tay-Sachs, a neurological disease that usually kills its victims before age 5.

A child can develop the disease only if both parents carry a relatively rare genetic mutation. Gammelgard said she had no clue she was a carrier; she hadn't been tested because she wasn't in the groups at highest risk.

She knows now. The couple raising the sick child contacted the agency that arranged Gammelgard's egg donation. The agency told her.

But neither she nor the agency has made any effort to inform the other families who used Gammelgard as a donor.

In the United States, nothing ensures that recipients of donated eggs or sperm are warned about defects later discovered in the donor's family tree. In contrast to blood donations, no one tracks donors and their products.

The system is founded largely on a pledge of confidentiality -- the promise that the donor and recipients will remain strangers, linked only through third parties. Donors typically sign contracts severing parental rights and most obligations.

But genetic ties endure. When flaws in DNA slip through the screening process, they may fan out over generations, undetected until it is too late.

Even if Gammelgard's other children do not have Tay-Sachs, they have a 50% chance of carrying the mutation. And these children, if they grow up to conceive babies with other Tay-Sachs carriers, have a 25% chance of passing along the disease.

For all Gammelgard knows, couples may have embryos made from her eggs in storage, awaiting implantation. Others may have conceived children she hasn't heard about.

"It's awful that in the United States right now, the buck stops with this young lady who donated," said Elizabeth Stephen, an associate professor of demography at Georgetown University who has studied the fertility industry. "There is no tracking system and no enforcement."

'A big family'

Bruce Steiger recalls telling Rick Karl on one of their first dates: "I want to have a family -- a big family."

Karl, raised as a conservative Catholic, had never considered the possibility. Over the years, Steiger convinced him that their well-paying jobs in the high-tech industry were going to get them only so far down the path to happiness.

"I've always considered having children to be pretty much out of the question, and that saddens me," Karl remembers telling Steiger one day in 2002 during a walk along the ocean in Long Beach. "So, if we can do this, let's go do it."

Through a gay parents group, they found an agency, Surrogate Alternatives in Chula Vista, that specialized in finding women to provide eggs and surrogates to carry the child, for a fee.

Such agencies typically are small, for-profit operations, drawing donors and surrogates through ads and clients via the Internet or word of mouth.