Organelles and Disease: Adrenoleukodystophy (ALD)

Understanding an Animal Cell: Basic Units of Life
The cell is the fundament unit of life. They make up the smallest level of a living organism in the human body, where the metabolic processes happen to in order to maintain life. It itself is considered a mini-organism made up from organs called organelles. These organelles are the structural and functional units and are created from several macromolecules connected together. A typical animal cell contains the following organelles (Tracey Greenwood, 2012): the nucleus (which houses the DNA), mitochondria (which produce energy), ribosomes (which make protein), the endoplasmic reticulum (for transportation) and the golgi apparatus (which distributes macromolecules). Animal cells also contain little digestive compartments, called lysosomes and peroxisomes, which break down macromolecules and gets rid of foreign bodies. See diagram below:

(Stein, 2008)

What is ALD?
Adrenoleukodystrophy (ALD), is a deadly genetic disorder that is quite rare affects 1 in 1800 (Foundation, 2004). The disease affects the adrenal glands & ‘White Matter’ of the brain by destroying myelin, the protective casing that surrounds the brain’s neurons. It causes progressive loss of physical and mental skills. It is a group of disorders caused by a defect of peroxisomes, which help to the brake down of fatty acids in the cells, resulting in very long chain fatty acids (VLCFA).
The most disturbing form of ALD emerges in childhood, normally between the ages of four and ten years old. Healthy boys unexpectedly begin to regress. At first, they show withdrawal or experience difficulty in concentrating. Then, as the disease destroys their brain, their symptoms get worse, including deafness and blindness, loss of muscle control, seizures and progressive dementia. Leading to either death or permanent disability, within 2 to 5 years from diagnosis.

There are three types of Adrenoleukodystrophy; Childhood cerebral ALD affects children who are between 4 and 10 years old. It progresses rapidly if the condition is not diagnosed early enough, Adrenomyelopathy (AMN), affects adult males and is milder than childhood cerebral ALD. But it progresses slowly by comparison and Addison’s disease, also known adrenal insufficiency. Addi-son’s disease develops when your adrenal glands don’t make enough hormones

Is it inherited?
ALD is an X-linked recessive disorder, meaning that only boys are affected and the mother may be a carrier of the disease. As human beings we have about 30,000 to 40,000 different genes, each has a function in making a person individual. The genes are arranged in pairs (one of the pair from each parent) on 23 chromosomes, some of these genes can be damaged.
The gender of the child will be determined by chromosomes that either contain XX (female) or XY (male). The damaged gene in ALD is on the X chromosome. Because females have two X chromosomes, the damage can be completely or partially oppressed by the other healthy X in the pair, but males however, do not have a second X chromosome to provide the working gene.
Most carriers of this faulty gene remain healthy, so unless other boys in the family have been affected there is no way of know who is a carrier.
Each pregnancy carries a (Group, 15):
• 25% chance of the child being an unaffected non-carrier girl
• 25% chance of the child being an unaffected carrier girl
• 25% chance of the child being an unaffected boy
• 25% chance of the child being an affected boy
Symptoms of ADL
Childhood cerebral ADL — Muscle spasms, seizures, difficulty swallowing, deafness, blindness, diffi-cultly comprehending, hyperactivity, paralysis, coma, loss of fine motor control, crossed eyed.
Adrenomyelophy (AMN) — Muscle weakness, stiffness in the legs, poor bladder control, difficulty thinking and remembering visual perceptions.
Addison’s disease — Loss of appetite, weight loss, decreased muscle mass, vomiting, muscle weak-ness, coma, darkening to areas of the skin colour or pigmentation.

Diagnosing ADL
Blood tests are taken to determine the levels of VLCFA present, with addition blood tests to con-firm that the ABCD1 gene mutation. Following this a magnetic resonance imaging scan (MRI) will need to be carried out to establish if the disease has started to cause damage to the brain, and if so to what level. The MRI scan will show the lesions on the brain caused by the damage of the myelin, even before any neurological or psychological symptoms are present. The MRI scan will create a Loes score, rating the severity of the damage to the brain on a scale from 0 to 34. A normal brain should have a score of 0.5 or less, whereas someone with severe ALD would have a score of 14 or more.

There are only two treatments currently available for Ardenoleukodystrophy: Lorenzo’s oil and stem cell transplantation;
Lorenzo’s oil was developed by Augusto and Michaela Odone in 1982. It combines two fats taken from olive and rapeseed oils and works by reducing the very long chain fatty acids that cause ALD, preventing further deterioration.
Stem cell transplantation sourced from umbilical cord blood (UCBT) or bone marrow (BMT) is considered for boys with a Loes score of 9 or lower. The aim being to give the patient healthy stem cells that will create functioning ALD protein, which they are lacking. These healthy proteins that enter the brain, stopping further damage. The patient requires chemotherapy or radiotherapy in order to reduce the risk of the transplantation being re-jected, leaving them more vulnerable to infection and increasing their mortality rate to 40%. Doctors will currently not perform stem cell transportation on patients with the adult form of the disease, Adrenomyelophy (AMN), as the risks of the treatment outweigh the benefits.
Scientists are currently working on several research programs; Gene Therapy, Mucomyst (Acetyl-cysteine), Alder Upregulation, Mesenchymal Stem Cell Therapy, Myelin Restoration and Antioxi-dants which it is hoped will offer more comprehensive treatments for ADL, especially Adrenomy-elophy (AMN).
The prognosis for patients with Childhood cerebral ADL is usually poor, unless bone marrow trans-plantation is performed early, due to progressive neurological deterioration. Death will usually oc-cur within 1 to 10 years after the first initial symptoms. Progression of Adult Adrenomyelophy will happen over decades.

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