What is MLD?

Part of a special report from the Tampa Bay Times on a rare genetic disorder. What is MLD? Metachromatic leukodystrophy or MLD is a rare genetic disease that causes part of a person's nerves to erode, eventually causing the body to shut down. Terminals Nerve cell How does it affect the body? Myelin Due to the genetic defect, patients with MLD are unable to produce an enzyme that normally breaks down fatty substances called sulfatides. Healthy myelin Sulfatides break down the myelin sheaths that insulate the The sulfatides' buildup and damage is usually most obvious in the brain, but they also accumulate in Sulfatides body's nerves. Deteriorated myelin cells of the damage spine, liver and kidneys. The breakdown damages the nerves that control major body functions and keeps the brain from connecting with the rest of the body. Brain What are the symptoms? Gradually, the disease takes over STAGE more of the body: Intellectual functions Memory starts to fade deteriorate I Usually, the first Hearing loss symptoms are subtle: Blindness STAGE Inability to speak Part of the body can go numb nervous system Seizures Loss of sensation in the extremities liver 3 Eventually, patients lose awareness of kidneys STAGE their surroundings A feeding tube becomes necessary and become unresponsive. Incontinence Loss of motor skills, such as the ability to walk. Eventual paralysis. How does MLD present itself? The disease shows up in three forms: late infantile, juvenile and adult. 60% to Percent of all afflicted by MLD per age group 50% 30% to 20% 20% to 15% Juvenile onset • Onset occurs between the age of 4 and adolescence. • Sometimes first noted during early school years when cognitive and behavior issues are observed. • Some individuals maintain mobility and cognitive skills for several years after onset. The decline is generally slower than in infantile cases. Adult onset • Onset occurs during teenage years and later. • Affected individuals alternate between periods of stability and decline that can last over 20 to 30 years. • First signs in this type of MLD are changes in gait, personality and cognitive skills. Late infantile • Onset at ages 1 to 2. • This is the most common form of MLD. • With this type of MLD, the child will at first have a few months of normal development, but he or she will then appear to regress as motor skills start to suffer. How do you get it? If two, often unsuspecting carriers have MLD is inherited as an autosomal recessive gene mutation. Both parents must be carriers. children, then the probabilities of their children Autosomal means that the genetic defect can be carried by both men and women. being affected by MLD are: Recessive means that if one of the genes in the pair is affected, the person will not have the condition but will be a carrier. U.S. statistics show: RR OR RO CI 25% 50% 25% chance they l in 100 l in 10,000 chance they will be a chance they will be will be people are carriers on Unaffected Carrier Affected chance of carriers becoming a couple unaffected by MLD (or 2 in 4) clear of MLD will suffer MLD average (or 1 in 4) (or 1 in 4) The condition can be more common in genetically isolated populations like Habbanite Jews, portions of the Navajo Nation and Arab groups because members of these communities are Thus, l in 40,000 are born affected by the condition (1 in 160,000 worldwide) historically more likely to have a child with someone within their cultural group. Diagnosis and prognosis There is no cure yet for MLD. The only way to know for sure if someone has MLD is to do a genetic test. MRIS and other scans may show symptoms that will point the medical professional toward recommending a genetic test. After you diagnose the disease, it's best to get the patient on medications to manage his or her symptoms and pain. 20 to 30 Research continues, but the prognosis for MLD is poor. Most people affected gradually deteriorate and typically die within a few years following the onset of symptoms: years in most cases of adult onset 10 to 20 years in most cases of juvenile onset Typical life expectancy after onset 1 to 5 years in most cases of infantile onset Resources for more information on MLD: • www.mldfoundation.org • www.nlm.nih.gov • www.nih.gov • www.ninds.nih.gov • www.rarediseases.org • www.ulf.org Visit: www.tampabay.com/savannah Savannah Hurst was a year old when the MLD symptoms started. Her parents watched as their baby went from babbling and dancing to lying in a wheelchair. Through it all, the Hursts have found a way to show Savannah the best of life. For them, the hardest of times aren't without smiles. Sources: mldfoundation.org, nih.gov, ulf.org, rarediseases.org, All Children's Hospital staff and doctors, mayoclinic.org Tampa Bay Times Graphic: Meredith Rutland, Lee Glynn | Times tampabay.com Research assistance: Natalie Watson