Long, interesting, scientific report

[Judith Richards <judithr@xxxxxxxxxxxxxxxxxxxxxx>]

very long, but worth the read...Parkinson's and Alzheimer's are mentioned.

>Mitochondria supply the body with energy, but they also may carry
>genetic diseases
by Faye Flam, Knight-Ridder Newspapers (KRT)

>PHILADELPHIA - In retrospect, Janine Swift had never been quite healthy.
>She didn't have much energy, rarely running or playing outdoors with other
>children, said her mother, Theresa, 41, of Collingswood, N.J.
>"As a little girl, her hands sometimes used to tremble," her mother said,
>but doctors could offer no explanation. "We thought maybe she was just a
>nervous kid."
>There was nothing to warn of the latent disease that would suddenly attack
>her nervous system in March 1995, when Janine turned 16, a disease
>surprisingly common - yet unknown to many doctors - that is pushing
>scientists to the limits of microbiology.
>First, Janine told her mother she had a headache, saw colored lights, and
>felt nauseated - classic symptoms of migraine headache. "The next day she
>was on the bathroom floor, having a seizure," said Swift.
>Over the next two years, the teen-ager's vision deteriorated. She became
>too weak to walk. The seizures, some lasting hours, kept coming,
>hospitalizing her for months. No one could figure out what was wrong.
>"We had EEGs, MRIs, spinal taps. ... We put her through all the tests," her
>mother said.
>Then, while taking a family history, a doctor at St. Christopher's Hospital
>for Children found that Theresa Swift herself had suffered some unexplained
>symptoms, starting a decade earlier, at age 30. Doctors thought it might be
>multiple sclerosis. At 35, she says, something happened to her vision
>-colors faded to white and stayed that way for weeks. First it happened in
>her right eye, then her left.
>Tests confirmed that Swift carried an abnormal gene that she had passed not
>only to her sick daughter but to two of her other three children as well.
>The gene causes a disorder Swift had never heard of - mitochondrial
>disease.
>In the teen-age daughter, the disease was wreaking havoc deep inside the
>cells of her body, destroying the microscopic structures called the
>mitochondria that normally combine molecules of food with oxygen, providing
>the body with energy.
>The same thing has been happening to the mother, only more slowly.
>Mitochondrial diseases affect 1,000 to 4,000 American children born each
>year, according to the Mitochondrial and Metabolic Disease Center at the
>University of California, San Diego. Most of the children die before
>adolescence.
>So far, dozens of different mitochondrial disorders have been identified,
>many with cumbersome names such as mitochondrial encephalomyopathy with
>lactic acidosis and stroke-like episodes, reflecting the baffling array of
>symptoms they produce - fatigue, headaches, seizures, strokes, diabetes,
>learning disabilities, slow growth, blindness and deafness.
>Doctors are still struggling to understand how mitochondrial disease works.
>They cannot offer a cure.
>"There's a feeling of helplessness because we're dealing with the unknown,"
>said Sharon Ditchey, a dietitian with two children who have been affected,
>one of whom died. Melissa, now 5, suffers from migraine headaches,
>arthritis, and deafness.
>As with other genetic defects, the problem is often inherited, but it can
>also happen spontaneously.
>The disease can come swiftly, as it does in some children. Or it can emerge
>gradually - in some cases, perhaps not until old age.
>New research shows that mitochondrial problems underlie Alzheimer's and
>Parkinson's diseases, as well as some cases of heart disease and
>adult-onset diabetes.
>And even in children, such as Janine Swift, mitochondrial disease often
>goes unnoticed until it reaches a critical point at which the deterioration
>of the mitochondria causes a breakdown of muscles or organs, including the
>brain and central nervous system.
>"It took one thing after another from her," said her mother. Two weeks ago,
>at age 18, she died.
>Though the first case of a mitochondrial disease was diagnosed in 1962, it
>was not until the mid-1980s that doctors began to recognize more cases in
>children. Experts now suspect that many patients are wrongly diagnosed as
>having cerebral palsy, epilepsy, multiple sclerosis, or "failure to
>thrive." It may even account for instances of sudden infant death syndrome.
>"We need to convince doctors these disorders are common and important,"
>said Douglas Wallace, an Emory University biologist who attended an
>international meeting on mitochondrial diseases last month in Philadelphia.
>"Until recently, it was considered stupid to look at the mitochondria" as a
>cause of disease, says Wallace. The changing attitude took a revolution in
>scientists' understanding of these tiny cellular power plants.
>High school textbooks have long depicted the mitochondrion as a folded
>ribbon surrounded by an oval-shaped membrane. The snapshot was accurate but
>the standard definition - an organelle, or tiny organ, with the job of
>making energy - didn't capture its strangely independent nature.
>In 1963 scientists discovered that the mitochondria carried their own set
>of genes, made from their own DNA. (Before that, scientists thought all
>human DNA was contained in the 23 pairs of chromosomes inside the cell's
>nucleus.)
>The genes in the mitochondria pass only from mother to offspring - egg
>cells carry mitochondria, while sperm cells do not.
>Stranger still, some scientists have come to see the mitochondria not as a
>standard part of our bodies but as a life form in itself - a benevolent
>parasite.
>The way Wallace explains it, about a billion and a half years ago, a
>slender, thread-like bacterium slithered inside a larger one-celled
>organism.
>Both life forms benefited from the invasion. The bacterium gained the
>protection and mobility of its much larger host, and the host benefited by
>absorbing some of the energy that the invader pumped out. The invader used
>an efficient, oxygen-burning process that the host cell had not evolved.
>This mutually beneficial - or symbiotic - partnership worked so well that
>the two evolved together into fungi, plants and animals.
>The discovery of the mitochondria's own set of genes backed this scenario
>of an independent origin, especially after analysis showed that the
>mitochondria's closest relative is a free-living bacteria.
>The late Carl Sagan noted the implications of this concept in Broca's
>Brain: "We are not single organisms but an array of about 10 trillion
>beings, and not all of the same kind."
>Emory's Wallace takes such thinking a step further, arguing that, as
>composite beings, we can die one of two ways - either the body's cells die,
>or the mitochondria within them die.
>He suspects that everyone's mitochondria are programmed to give out at some
>point, usually in old age. In other words: "Mitochondrial diseases might
>be the most common cause of death."
>According to Wallace's view, aging is just a slower version of childhood
>mitochondrial disease. First, the deteriorating mitochondria may make an
>aging person feel tired, but once the damage passes a critical threshold,
>various organs give out. If the damage first affects the brain, it may show
>up as Alzheimer's or Parkinson's diseases.
>Some drugs that are aimed at killing viruses also poison the mitochondria,
>says Robert Naviaux of the University of California, San Diego.
>Some cases of mitochondrial disease come from drugs aimed at attacking
>viruses. One example, says Naviaux, is the AIDS drug AZT, whose side
>effects, he says, come from its attack on mitochondria. And about five
>years ago, an experimental hepatitis B drug, fialuridine, unexpectedly
>killed 5 people in a drug trial. Their mitochondria had been irreparably
>damaged.
>At the Philadelphia meeting, about 170 researchers and 200 parents focused
>on the childhood diseases.
>The most notable area of progress: The finding that certain restrictive
>diets and vitamin supplements can relieve symptoms in some children.
>That knowledge has been some help for another mother at the conference,
>Eileen Murphy of San Diego. Murphy says she and her husband struggled to
>get their baby to drink more than a few drops of formula at a time.
>Doctors told Murphy it was just first-time-parent anxiety. Her baby,
>Cristin, didn't look wasted. "She had these chubby little cheeks," said
>Murphy, but the child seemed listless.
>By her 13th month, Cristin hadn't made progress toward walking or talking.
>Doctors thought she had cerebral palsy - a diagnosis usually foreshadowing
>a life of physical and mental disability.
>"I was devastated," said Murphy, who started to search for other diagnoses,
>combing medical literature, surfing the Internet, and crisscrossing the
>country to meet doctor after doctor.
>Eventually, a gastroenterologist made the diagnosis.
>"When I realized she was dying," said Murphy, "then I wished it could have
>been just cerebral palsy."
>In Cristin's case, the problem was an inability to break down fats. Instead
>of working toward energy and growth, molecules of fat were lodging in her
>muscles, explaining her floppy limbs and chubby cheeks.
>Murphy says that after fat was cut from Cristin's diet, the girl - now 3 -
>has gained weight and started walking. Still, Cristin's doctors don't
>expect her to survive to adolescence.
>In an effort to help her daughter, Murphy quit her job as an engineer for
>Hewlett-Packard, studied microbiology, and now works with the mitochondrial
>research group in San Diego.
>Wilmington, Del., couple Marsha and Allen Barnett have also made it their
>mission to raise public awareness and to increase research funding. In the
>early 1980s, the couple lost two of their three sons to a mitochondrial
>disorder called Leigh's disease. Michael was 10 and Charles was 6.
>The couple started the Michael and Charles Barnett Memorial Fund, raising
>money for a mitochondrial research center at St. Christopher's.

>For more information on mitochondrial disorders, call United Mitochondrial
>Disease Foundation, Monroeville, Pa. 412-856-1297.
>(c) 1997, The Philadelphia Inquirer.
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