DNA Test on Baby Goes Against County in Suit

In a stunning turnaround, a DNA test performed on tissue from a baby who died nearly 17 months ago from an undiagnosed birth defect has forced the county of Los Angeles to back down from its contention in a medical malpractice lawsuit that the baby was switched.

Although the test could not definitively prove that Patty Chavez was the mother of Steven Ruiz, it showed that she and her boyfriend, Reynaldo Ruiz, could have been the baby’s parents.

Assistant County Counsel Robert Ambrose said Tuesday that the results provided the “conclusive proof” the county had sought that Chavez and Ruiz were the baby’s parents and that the matter would now go before a judge who would help the parties reach a settlement.

“There’s been enough on this,” Ambrose said. “We would like to see if we can conclude it if we can.” Told of the test results by her attorney, Chavez said: “When I heard I was jumping up and down. . . . I just started crying for all the happiness that I had. It’s been really hard, with people blaming me and all. . . . But I just knew they were going to say that the baby was mine because it was.”

Although the couple’s attorney, Aileen Norvell Goldstein, had sued the county for $250,000, the maximum award for medical malpractice, she said she thought Chavez and her family deserved more.

“I’m ecstatic for this girl and for her family that this thing is behind them . . . and they are not forced to exhume their baby and that . . . the county has completely conceded that they are wrong,” she said.

Chavez and Ruiz, who live in Northridge, have claimed nurses and doctors at the county’s Olive View Medical Center in Sylmar failed to diagnose a congenital condition that left the baby with no anal opening. Attorneys for the county had maintained in court papers that Steven Ruiz was not the baby born to Chavez five days earlier at the county’s Olive View Medical Center in Sylmar.

After the case became public earlier this month, the county acknowledged that it had not thoroughly investigated its claims that the baby who died at Northridge Hospital Medical Center was not the same one born at Olive View. The county had maintained that minor discrepancies in medical records at Olive View and at the county coroner’s office showed that there were two babies.

Blood samples and gum scrapings from Chavez, 17, and Ruiz, 21, were tested Tuesday by a USC pathologist and were compared with tests on the baby’s tissue sample.

Known as PCR, or polymerase chain reaction, the test uses heat and bacteria found in natural thermal pools to amplify the DNA patterns that can provide clues to a person’s identity from a sample as small as a hair follicle.

But the tissue in this case had been stored in a formaldehyde solution by the county coroner’s office and scientists and attorneys disputed whether a PCR test performed on such a sample could be reliable.

Ambrose had said earlier Tuesday that the county would accept the results of the test--to be performed by a USC pathologist--whether it bolstered its case or not.

The county last week ordered the PCR test on the preserved tissue sample after Goldstein threatened to have the baby’s remains exhumed from San Fernando Mission Cemetery and tested to prove her clients were the parents.

Goldstein said, however, that formaldehyde might have hindered the reliability of the test and that her clients would resume their demand for an exhumation if the DNA test results had not been in their favor. She would then have had tests done by a private laboratory.

Traditional DNA testing methods are widely used in court cases because they can provide a certain match, similar to a fingerprint, between a specimen taken from a crime scene and blood or tissue from an accused criminal.

A scientist can use that test, known as RFLP, to line up strands of DNA from each sample side by side for comparison of their distinctive markings. The test, however, relies on analysis of long strands of genetic material, which means that a relatively large amount of intact DNA is required, and it also takes weeks to complete.

PCR, on the other hand, is considered valuable because it is quicker and can make use of old or damaged samples. PCR allows a scientist who only has a trace of genetic material available to obtain enough for reliable analysis by making millions of copies.

The test’s disadvantage is that it is less precise. It cannot establish a match, as RFLP could, but instead can identify a person’s DNA as being in one of 21 categories. Those categories occur with varying frequency in the population--between .5% and 40%--and so the reliability of the identification is also measured by those percentages.

Ambrose said he did not know in which category Chavez and Ruiz or the baby fell.

“We will not seek any further testing or go to any further source for testing,” he said. “The bottom line is that it did not exclude these plaintiffs as parents and we have accepted that conclusion.”

Despite drawbacks with PCR tests, the method has been admitted in at least 29 court cases in 15 states, according to Cetus Corp. of Emeryville, Calif., which developed the PCR test.

Yet, even some scientists who tout the value of PCR were skeptical that it could produce reliable results on tissue preserved in formaldehyde.

Chemical preservatives prevent tissue from decomposing, but they also gradually break down DNA strands, said Ivan Balazs, director of research and development at Lifecodes Corp., a New York biotechnology firm. That’s particularly important in PCR tests, Balazs said, because they rely on the ability to reproduce millions of copies of small strand segments.

But geneticists and pathologists said that even formaldehyde preserved tissue would not make the PCR test produce an inaccurate result. Rather, such a sample would not produce any result at all.