ADRENOLEUKODYSTROPHYWHAT IS ALD?
Adrenoleukodystrophy (ALD) is a disease that affects the central nervous system of children and adults who inherit the genetic defect. The myelin sheath, an important component of brain cells, is degraded, and can cause eventual paralysis. The most common form of ALD is X-linked, which means that symptoms manifest primarily in males. Females that carry the gene defect have a 50% chance of passing it onto their sons, and may also show some mild symptoms.
WHAT HAPPENS IF YOU HAVE ALD
Characteristic symptoms and severity varies with ALD subtype. Symptoms have been categorized into anatomical area below.
1. THE BRAIN
In C-ALD, rapid inflammation and demylination occur in the brain. Cognitive dysfunction, such as learning difficulties and behavioural changes, is also one of the initial symptoms.
2. THE NERVOUS SYSTEM
In AMN, general progressive myelinopathy (disease of the myelin) within the spinal cord occurs, leading to issues in the lower body such as walking disabilities, sensory dysfunction and bladder issues.
3. THE ADRENAL GLANDS
Most forms of ALD are associated with adrenocortical dysfunction. This means that hormone balance and production are affected.
4. THE LEGS
Early affected children will lose their ability to walk. In adult forms, males (including some females) may suffer from progressive muscle stiffness or weakness, leading to a range of disability severities.
PASSING IT ON
Females carry two X-chromosomes and males carry one X and one Y-chromosome. One sex chromosome from each parent is passed down to their offspring.
In ALD-affected females, one of the two X chromosomes are mutated. This means that there is a 50% chance of passing on a mutated X chromosome to either a son or daughter. Because females have two X-chromosomes, the normal variant from the father prevents them from expressing disease characteristics, but are instead carriers of the disease.
In males, however, there is only one X-chromosome. If males inherit the mutated X-chromosome from the mother, they express the disease characteristics.
ON A CELLULAR LEVEL
In a non-diseased setting, healthy neurons (cells that make up the nervous system) have 3 main parts: the cell body, the axon and dendrites. Any physical action originates from the brain and is transferred as electrical messages from cell to cell until it reaches the muscle. The myelin sheath is a fatty layer that surrounds the axon length, facilitating fast signal transfer between cells.
In ALD, the myelin sheath layer is degraded, impeding the signal transfer between cells, resulting in gradual paralysis of the individual. It is known that inflammation and/or the accumulation of a specific type of fat molecule (very long chain fatty acids, or VLCFAs) contributes to the demyelination process, but the exact mechanism is unknown.
TAKING RESEARCH TO THE NEXT LEVEL
ALD is a rare genetic disease with an incidence rate of 1 in 18 000 births. This makes it difficult for clinical scientists to thoroughly investigate the origin and evolution of this disease. Furthermore, because ALD is rare, medical research funding is less often allocated for the required resources relative to other types of research projects.
Gathering ALD affected families together will help to advocate for more effective research into treatment and preventative measures. Together, we can identify the dedicated champions in medical research and provide support where possible. In this way, we can help to ensure the research field is moving forward.
ALD is a swiftly progressive disease. 45% of ALD cases result in death within the first 5 years of age in an affected male. The optimal window of medical intervention is short. In addition to this, female carriers of ALD are reaching their reproductive peak in the age of fast developing technology. The time to support is now.
Technology is within our reach. Advanced genetic screening and in vitro fertilization are just a few options that are becoming readily available to expecting ALD moms to change management during pregnancy. Resource awareness and support is a first step in our plan of action.
ALD affected families are few and far between. They are widespread globally, but not localized to one another to form meaningful communities.
Using Solving X as a platform, we can connect and form peer-to-peer relationships. As ALD affected individuals, supporters, parents or friends. We want you to know that you are not alone.
INCIDENCE OF AFFECTED MALE BIRTHS
AFFECTED CHILDREN UNDER 5 YEARS OLD
PROBABILITY OF GENE TRANSMISSION
AVERAGE AGE OF DIAGNOSIS
“I can’t believe it took us this long to get started. So happy that we did.”
Olivia Viola, Co-Founder
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