Down syndrome in a true light

“The Memory Keeper’s Daughter,” Lifetime premiere April 12, 9 p.m.

The premise: In 1964, Nora Henry (Gretchen Mol) goes into labor in the middle of a snowstorm and her husband, David, a physician, must deliver his own child. Dr. David Henry (Dermot Mulroney) delivers fraternal twins, a boy and a girl, and the girl has Mongoloid features. Nora is groggy from anesthesia and is not aware of what is happening as David, who endured watching his own sister die of birth defects, decides to send the Down child (in 1964 it was still called Mongolism) away with his nurse, Caroline (Emily Watson), to spare his wife the pain of raising a mentally disabled child. David tells his wife that her daughter died, and Caroline raises the baby, Phoebe, as her own daughter. The child is only mildly retarded, has no heart defects or other major medical problems and, at age 6, can dress herself, write the alphabet and count to 50. Caroline fights to get her into school, which was generally not provided for children with Down syndrome at that time.

The medical questions: What is Down syndrome and are children with the condition immediately identifiable at birth? Is the condition possible with twins? Do these birth defects tend to run in families? Was amniocentesis, or other screening methods that can reliably detect Down syndrome, routinely available in 1964? What are the most common medical and neurological manifestations of Down syndrome? Are there cases as mild as Phoebe’s?

The reality: Down syndrome is a genetic condition that results from the presence of an extra chromosome 21, so that there are three rather than two of these chromosomes in every cell. Genetically this is known as trisomy 21. Heart malformations occur in about half; Phoebe is in the group that lacks them. The syndrome has characteristic physical features including epicanthic folds (extra skin on the inner side of the eyelid), a flat nose, up-slanted palpebral fissures (the eyes slant up), a low hairline in the back, small ears, a protruding tongue, brachycephaly (extra wide head), nuchal folds (skin folds at the back of the neck), a crease across the palm of the hand, and a curve of the fifth finger toward the fourth. Those with Down syndrome suffer from mental retardation and poor muscle tone, especially when they are young. An experienced observer can often identify Down syndrome at birth based on noticing some of the above features -- in Phoebe’s case, David Henry appears to notice her slanted eyes and creased hands, as well as her extra wide head.

Down syndrome is certainly possible in twins, but if identical, both would generally be affected, and if fraternal, as is the case with Phoebe, only one would usually be affected. Down syndrome doesn’t run in families, though in a small percentage of cases, material from one chromosome 21 gets stuck onto another chromosome, and the condition can then be inherited. But the birth defect that caused the early death of David Henry’s sister, “hole in her heart,” is not related to Down syndrome.

Amniocentesis, which is one of the standard tests to detect genetic abnormalities in utero, was not commonly used until the 1970s, so it is not surprising that Phoebe wasn’t diagnosed until birth.

“Mental retardation is always present in a Down syndrome child, though there is great variability in cognitive abilities and mild cases like Phoebe’s certainly occur,” says Dr. Charles J. Epstein, a pediatrics professor at UC San Francisco. “I have seen and known people with Down syndrome who cannot talk at all and ones who can give a motivational lecture, write a book, or play the piano.” David, by abandoning his child, doesn’t get to see the delightful functioning young adult she develops into.

Since the 1960s, better medical care, social acceptance and improved educational opportunities have helped people with Down syndrome reach their potential. Unfortunately, adults with Down syndrome have a high risk of developing early Alzheimer’s disease, and by the time they reach their 60s, close to 50% show evidence of dementia.

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Dr. Marc Siegel is an internist and an associate professor of medicine at New York University’s School of Medicine. He is also the author of “False Alarm: The Truth About the Epidemic of Fear.” In the Unreal World, he explains the medical facts behind the media fiction. He can be reached at marc@doctorsiegel.com.