MLD a Rare and Serious Progressive Disease
Marc Patterson, MD, Mayo Clinic
DEAR MAYO CLINIC:
What can you tell me about metachromatic leukodystrophy? My granddaughter was just diagnosed but she has two older siblings who are perfectly healthy. How is that possible?
Metachromatic leukodystrophy (MLD) is an inherited disorder that affects the protective covering around nerve cells (myelin sheath), as well as the nerve fibers that the sheath insulates and protects. A rare, serious and progressive disease, MLD currently has no cure. But treatment may help delay the disease's progress, and research is exploring new treatment possibilities for MLD.
MLD is caused by defective genes. But not everyone who inherits a defective gene associated with MLD develops the disease. To understand why, it's helpful to know some background on how genetic disorders work. Genes come in pairs. For each pair, we inherit one from our father and one from our mother. MLD is inherited in a recessive fashion. That means for a person to develop the disease, both inherited genes associated with MLD must be defective. If a child inherits only one defective gene, he or she is a carrier of the disease, but is unlikely to develop MLD. Assuming neither of your granddaughter's parents have MLD, they must both be MLD carriers.
Because carriers only have one defective gene, and because the set of genes one child inherits isn't exactly the same as a sibling's, children of the same parents can be affected differently by a recessive genetic disorder such as MLD. Your grandchildren who don't have MLD either inherited only one defective gene (making them MLD carriers), or perhaps they received two normal genes and aren't affected at all. When both parents carry gene mutations that cause recessive genetic disorders and have children, chances are one in four that each child they conceive will be affected.
Due to the genetic defect they've inherited, people who have MLD are missing the enzyme arylsulfatase. Arylsulfatase is one in a group of enzymes that help recycle molecules which make up the myelin sheath. Without that enzyme, fatty materials (lipids), sugars and proteins build up within the recycling centers of cells (lysosomes). This accumulation causes the myelin sheath and its underlying nerve fibers to break down.
Areas most affected by MLD include the nervous system, liver and kidneys. The signs and symptoms of MLD get worse over time. Common MLD symptoms include abnormal muscle rigidity and movement (spasticity), inability to walk, seizures, and blindness. Children with MLD often experience developmental delays and progressive mental impairment. Psychiatric symptoms may be the first sign of the illness in adults.
MLD can strike from infancy through adulthood. The three forms of the disease are based on when symptoms begin. Late infantile MLD, the most common form, usually begins around ages 1 or 2. Juvenile MLD typically appears between ages 4 and 12. Adult MLD can begin during the teen years, but in some people may not appear until the 40s or 50s.
Diagnosing MLD usually involves MRI scans of the brain, which typically show changes in the myelin sheath and nerve fibers (white matter) of the brain's hemispheres. A blood test that reveals low or absent activity of arylsulfatase confirms an MLD diagnosis.
Because it's a progressive disorder and no cure is available yet, treatment of MLD often focuses on managing the symptoms. Stem cell transplantation may slow the disease, if begun during MLD's early stages, but no treatment is curative. MLD is inexorably progressive, and leads to premature death in all cases. Additional treatments are under investigation. One significant area of research is examining the feasibility of enzyme replacement therapy that could do the work of the missing arylsulfatase enzyme.
Medical Edge from
Available at Amazon.com:
- MLD a Rare and Serious Progressive Disease
- Sleep Apnea: Keeping Up the Positive Pressure
- Alternatives to Statins for Lowering Cholesterol
- Recurrence of Basal Cell Carcinoma Uncommon After Mohs Surgery
- Can Surgery Treat Type 2 Diabetes?
- Self-Care Techniques to Relieve Discomfort From Buttock Pain
- Artificial Lenses Have Long Been Used to Correct Vision
- Gene Mutation That Causes Huntington's Can Occur Spontaneously
- Is It Better to Stop Smoking Abruptly or Gradually?
- Brain Scan Alone Cannot Predict Likelihood of Dementia
- Is Sunscreen Dangerous? 4 Sun Protection Dos And Don'ts
- Low Platelet Count Not Necessarily Reason to Postpone Surgery
- Could Swimming in Cool Water Cause a Heart Attack?
- Bringing Psoriasis Under Control
- Best Summer Foods for Sensitive Stomachs
- Fight the Common Mold Allergy
- Largest Ever Cell Phone Cancer Study is Inconclusive
- Treating Early-Stage Esophageal Cancer
- TNF Inhibitors Offer Relief to Those With Rheumatoid Arthritis
- Prostate Exam Good First Stop When PSA Levels Increase
- 7 Nasty Germs That Could Land Your Kid in the Hospital And How to Avoid Them
- Secondhand Smoke A Serious Public and Personal Health Problem
- What to do About Excessive Belching and Feeling Full?
- Chest Pain: A Heart Attack or Something Else?
- Screening Plays Key Role in Detecting Polyps Before They Become Cancerous
- Learn How to Read Supplement Labels
- Compression-Only CPR Can Replace Conventional CPR in Many Circumstances
- Diabetes: Could You Have Diabetes and Not Know It
- Fighting Inflammation with Food
- Cortisone Injections Unlikely to Have Negative Affect on Bones
- Bad Health Habits Rob Years From Life Span
- The Importance of Decreasing Dietary Sodium
- Chronic Obstructive Pulmonary Disease (COPD): Takes Your Breath Away
- 7 Ways to Prevent Heart Disease
- Hypotension or Stiff Arteries May Cause Low Diastolic Blood Pressure
- Is It OK to Travel to a High Altitude With High Blood Pressure?
- Existing Drugs to Treat Herpes Are Very Effective
- Dry Mouth Can Be a Serious Problem
- 6 Simple Ways to Improve Symptoms of Fibromyalgia
- All About Gout: Old Disease Becoming More Common
- Frequent Monitoring Critical to Effectively Manage Scleroderma
- How to Identify Suicide Risk Before It's Too Late
- Tips for Natural Allergy Relief
- Inflammation May Play Role in Irritable Bowel Syndrome
- Bouncing Back After Being Sick
- Nicotine Patch May Offer Some Benefit to Ulcerative Colitis
- Common Myths and Misconceptions About Diabetes
- Vitamin E Supplements Not Recommended for Those With Diabetes
- Tick-Borne Disease Risk Peaks in Spring and Summer
- Meibomitis Creates Receptive Environment for Bacteria
- Top 4 Seasonal Allergy Mistakes
- Stress Less: Ten Strategies That Work
- Paralyzed Limbs Revived by Hacking Into Nerves
- Can Acid Reflux Damage my Esophagus
- Treadmill Test Can Reveal Hidden Problems in Heart
- Suffering From Allergies? Tailor Treatment to Your Symptoms
- Researchers Break Through to Unconscious Patients
- Key Factors Related to Heart Attack Risk
- Type 2 Diabetes Increases Risk for Cardiovascular Problems
- Hypochondria: The Impossible Illness
- Surgeries Can be Combined But May Not be Necessary
- Is Heartburn Surgery the Answer?
- Best Cooking Methods for Heartburn Sufferers
- 14 Things You Might Not Know About Aspirin
Copyright © 2010 Mayo Clinic. All rights reserved.