Friday, March 7, 2008

Melungeon Myth: Joseph's Machado Disease

by Janet Crain

The following statement is an example of the kind of Melungeon Myths being found on the Internet. These statements are being used as an attempt to link Melungeons to non-existent Turkish ancestors and do not bear close scrutiny.

"Modern-day Melungeons have found an intriguing link between their peculiar diseases and those of eastern Mediterranean. Diseases identified in the Melungeon population include thallasemia, Behcet's Syndrome, Machado-Joseph(Azorean) Disease, sarcoidosis, and Familial Mediterranean Fever."


This blog will address the validity of each of these claims. Today we are taking a look at the Machado-Joseph (Azorean) Disease claim. In 2004, in spite of the statement by author Brent Kennedy that a half dozen Melungeon descendants in Tennessee had this rare and debilitating disease, Dr. Marie Boutte of the University of Nevada-Reno, who studies genetic diseases, particularly Machado-Joseph Disease, was not able to find a single case in a person of Melungeon descent anywhere. Her search was to continue and to date nothing more has been heard.

Machado−Joseph disease

Machado−Joseph disease (MJD) is an autosomal dominant, multisystem neurodegenerative disorder involving predominantly cerebellar, pyramidal, extrapyramidal, motor neuron and oculomotor systems. Although it was first reported in families of Portuguese−Azorean descent, MJD has also been described in non−Azorean families from various countries, being one of the most common hereditary spinocerebellar degenerations. With the use of highly polymorphic microsatellite DNA polymorphisms, we have assigned the gene for MJD to the long arm of chromosome 14 (14q24.3−q32) by genetic linkage to microsatellite loci D14S55 and D14S48 (multipoint lod score Zmax=9.719).

What is Machado-Joseph Disease?

Machado-Joseph disease (MJD)-also called spinocerebellar ataxia type 3-is a rare hereditary ataxia. (Ataxia is a general term meaning lack of muscle control.) The disease is characterized by clumsiness and weakness in the arms and legs, spasticity, a staggering lurching gait easily mistaken for drunkenness, difficulty with speech and swallowing, involuntary eye movements, double vision, and frequent urination. Some patients have dystonia (sustained muscle contractions that cause twisting of the body and limbs, repetitive movements, abnormal postures, and/or rigidity) or symptoms similar to those of Parkinson's disease. Others have twitching of the face or tongue, or peculiar bulging eyes.

The severity of the disease is related to the age of onset, with earlier onset associated with a more severe form of the disease. Symptoms can begin any time between early adolescence and about 70 years of age. MJD is also a progressive disease, meaning that symptoms get worse with time. Life expectancy ranges from the mid-thirties for those with severe forms of MJD to a normal life expectancy for those with mild forms. For those who die early from the disease, the cause of death is often aspiration pneumonia.

The name, Machado-Joseph, comes from two families of Portuguese/Azorean descent who were among the first families described with the unique symptoms of the disease in the 1970s. The prevalence of the disease is still highest among people of Portuguese/Azorean descent. For immigrants of Portuguese ancestry in New England, the prevalence is around one in 4,000. The highest prevalence in the world, about one in 140, occurs on the small Azorean island of Flores. Recently, researchers have identified MJD in several family groups not of obvious Portuguese descent, including an African-American family from North Carolina, an Italian-American family, and several Japanese families. On a worldwide basis, MJD is the most prevalent autosomal dominant inherited form of ataxia, based on DNA studies.

Disclaimer:This article is not intended to provide medical advice or diagnosis. Consult a medical health professional if you think you might be suffering from a medical condition.

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