Prevention and Genetic Testing

Prevention of Adrenoleukodystrophy

There is no way to prevent ALD. Parents who have a history of ALD in their family can undergo genetic counseling when deciding to have a child. By doing this parents are able to get genetically tested to determine if they carry the gene that could be passed on to their offspring. Female carriers can be diagnosed 85% of the time using a very-long chain fatty acid test and a DNA probe study done by laboratories. 

If a child is born with ALD early recognition and treatment may prevent the development of clinical symptoms. Lorenzo’s oil has been shown to be a significant treatment option in young boys. There are also new technologies being developed to allow detection of ALD through newborn screening. A prenatal diagnosis for adrenoleukodystrophy is currently available which evaluated the cells from the chorionic villus or amniocentesis.

Genetic testing for Adrenoleukodystrophy

About 93% of index cases have inherited the ABCD1 mutation from one parent; at most, 7% of individuals with X-ALD have a de novo (Latin expression meaning "from the beginning,") mutation. Affected males transmit the ABCD1 mutation to all of their daughters and none of their sons. Carrier females have a 50% chance of transmitting the ABCD1 mutation in each pregnancy. Males who inherit the mutation will be affected; females who inherit the mutation are carriers and will usually not be seriously affected. Carrier testing of at-risk female relatives and prenatal testing for pregnancies at increased risk are possible if there is a family history of ALD.

CCALD - childhood form ALD
AMN - neurological ALD

References

Hugo W Moser, M.D. Ann B Moser, B.A. Steven J Steinberg, Ph.D. and Stephan Kemp Ph.D. Database X-ald; Adapted from; http://www.x-ald.nl/clinical-diagnosis/genetics-and-counseling/

Moser A., Steinberg J. & Raymond, G. 1999. X-linked Adrenoleukodystrophy. Gene Reviews; Adapted from http://www.ncbi.nlm.nih.gov/books/NBK1315/

Kaneshiro N. & Zieve D. 2009. Adrenoleukodystrophy – Prevention. University of Maryland Medical Center; Adapted from http://www.umm.edu/ency/article/001182prv.htm


Alisha M.

Dietary Management

It is recommended for patients diagnosed with ALD to consume diets low in very-long chain fatty acids (VLCFA) and in conjunction with Lorenzo’s Oil under the supervision of a physician and dietician. Fatty acids are necessary chemicals in the body and can be found in the form of triglycerides, phospholipids, sphingolipids, and glycolipids. All of these forms can be found in cells, or can compose the cell by forming the cell membrane. The body has developed methods on removing fatty acids if they are in excess through the process of β-oxidation. When there is an impairment in the breaking down process, disease often occurs, and in this case, ALD. VLCFA’s are necessary to form parts of the brain membrane, such as myelin. When the body makes too much, and is unable to remove excess amounts, increased levels if C26:0 are seen in ALD.

The normal American diet consists of roughly 12 to 40mg of VLCFA. A study analyzed whether reducing exogenous intake of VLCFA to 3 mg per day would effectively lower C26:0 levels in plasma. Administration of the very long-chain fatty acid restricted diet to 7 adrenoleukodystrophy patients for a 3 to 24 month period was found to be ineffective in lowering plasma VLCFA or in improving clinical status. This may be due to the high endogenous synthesis of C26:0 (demonstrated in fibroblast cells) by elongation of shorter chain fatty acids and may account for failure of dietary therapy.

Hexacosanoic Acid (C26:0)

Plant oils are the richest sources of VLCFA (208mg/100g) while peanut oil has the highest content (tablespoon of peanut oil has 12mg of C26:0). Other foods high in VLCFA are whole-grain or bran cereals, pita bread, and unpeeled fruits (waxes are principal sources). Fish, meats, poultry and eggs contain less than 1mg/100g.

References:

http://www.x-ald.nl/biochemistry-genetics/vlcfa/

Kishimoto Y., Moser HW, Kawamura N, Platt M, Pallante SL, Fenselau C (1980) Adrenoleukodystrophy: Evidence that abnormal very long chain fatty acids of brain cholesterol esters are of exogenous origin. Biochemical and Biophysical Research Communications 96(1): 69-76.

Moser HW, Borel J (1995) Dietary Management of X-linked Adrenoleukodystrophy. Annual Review of Nutrition 15: 379-397.

Van Duyn MA et al. (1984) The design of a diet restricted in saturated very long-chain fatty acids: therapeutic application in adrenoleukodystrophy. The American Journal of Clinical Nutrition 40: 277-284.

Prevalence and Incidence

Prevalence and Incidence of Adrenoleukodystrophy 

Prevalence is a frequently used epidemiological measure of how commonly a disease or condition occurs in a population. Prevalence measures how much of some disease or condition there is in a population at a particular point in time. The prevalence is calculated by dividing the number of persons with the disease or condition at a particular time point by the number of individuals examined. 


The incidence of a disease is another epidemiological measure. Incidence measures the rate of occurrence of new cases of a disease or condition. Incidence is calculated as the number of new cases of a disease or condition in a specified time period (usually a year) divided by the size of the population under consideration who are initially disease free. 


It has been found that the prevalence of adrenoleukodystrophy or the number of individuals with this disease is 1 in every 200,000.


The incidence was approximated to be 1 in every 100,000.


This disease has also been found in all races and on all of the continents. 


Keep in mind that these estimates are referring to all the forms of adrenoleukodystrophy, the child and adult forms. 


References


http://www.rightdiagnosis.com/a/adrenoleukodystrophy/prevalence.htm 


http://ghr.nlm.nih.gov/condition/x-linked-adrenoleukodystrophy


Alisha M.

Stages

Classic childhood form (X-linked adrenoleukodystrophy)

In this case of ALD, the child usually develops normally usually up to 3 or 4 years of age. The first noticeable problems are behavioral changes such as hyperactivity, difficulty paying attention, aggression, poor academic performance, difficulty reading and comprehending and abnormal withdrawal. In this stage, children are most often misdiagnosed with ADHD. As the disease progresses, more serious difficulties occur such as loss of hearing and vision. The child is unable to discriminate sounds and has difficulty understanding speech. Also, they may develop an inability to see visual information on the left or right side, may not be able to see clearly, and double vision. This eventually leads to deafness and blindness. ALD patients will then experience difficulty walking, swallowing, have learning impairments such as poor memory, difficulty in speech articulation due to the inability to control muscles involved in speech, fatigue and seizures. About 33% of patients with ALD develop seizures, which may be the first sign of ALD. 90% of children develop insufficient production of hormones by adrenal glands by the time signs of the disease are first noticed. From the onset of the initial symptoms, patients can be in a vegetative state within 6 months to 2 years, although rate of progression varies in different patients. Death can occur anytime after symptoms begin, but usually occur within 1 to 10 years.

Adult-onset form (adrenomyeloneuropathy)

This form of ALD usually occurs between the ages of 21 and 35. It progresses more slowly than the childhood form, with the first symptoms being stiffness and weakness in legs that worsen over time. Patients develop ataxia (impairment in coordinating movements), difficulty walking, sensory loss, and loss of bladder control (no sphincter control). About half of patients show brain damage, with 33% having myelin loss, and 10-20% showing severe brain damage. This usually results in total disability and death. 70% have insufficient production of hormones by the adrenal glands. This type of ALD usually progresses over a 5 to 15 year period, but can go progressing for decades.

Nevena V.

References:

http://www.medfriendly.com/adrenoleukodystrophy.php5

Moser MW, Mahmood A, Raymond GV (2007) X-liked adrenoleukodystrophy. Nature Review 3(3): 140-151.

Hematopoietic Stem Cell Gene Therapy with a Lentiviral Vector

As discussed beforehand, ALD is a disease deficient in the ALD protein, an adenosine triphosphate-binding cassette transporter encoded by the ABCD1 gene involved in fatty acid degradation.  Researchers have found a novel way to replace this dysfunctional gene with the wild-type by using meas of gene therapy. Many of the therapies for ALD today involve bone marrow transplantation. The long-term benefits of bone marrow transplantation are mediated by the replacement of brain microglial cells derived from donor bone marrow myelo-monocytic cells. Unfortunately, bone marrow transplantation carries a high risk of mortality and it can be expecially difficult to find a matched donor. Researchers introducing gene therapy has reasoned that hematopoietic stem cell gene therapy can be a more appropriate therapeutic alternative.

In this therapy, CD34+ cells were removed from two patients and a lentiviral vector encoding the wild-type ABCD1 gene was infused into the hematopoietic cell and then reinfused back into the patients. An HIV-derived vector was used to deliver the therapeutic gene into patients cells.

After 24 to 30 months, there was a detected polyclonal reconsitution with 9 to 14% of granulocytes, monocytes, and T and B lymphocytes expressing the ALD protein.

In the graphs protrayed above, there is an increased percentage of lymphocytes/monocytes, and CD+ cells expressing the ALD protein. There is also a decreased concentration of C26:0/C22:0 fatty acids after gene therapy.

14 to 16 months after infusion, MRI scans show progressive demyelination stopped as depicted below.

Nevena V

References:

http://www.sciencedaily.com/releases/2009/11/091105143706.htm

Cartier N. et al. (2009) Hematopoietic Stem Cell Gene Therapy with a Lentiviral Vector in X-linked Adrenoleukodystrophy. Science 326: 818-823.

Treatment with Lorenzo's Oil

Lorenzo’s Oil is a 4:1 mixture of glyceryl trioleate (oleic acid - monounsaturated fatty acid) and glyceryl trierucate (erucic acid - monounsaturated fatty acid). It has been found that oral administration of this oil in cerebral ALD patients is able to successfully normalize levels of VLCFA in the plasma, only for boys that are largely asymptomatic. There therapy was first introduced in 1981, with intentions to reduce the level of very long chain fatty acids (VLCFA) in the plasma. It was found that a diet alone with reduced intake of saturated VLCFA did not alter plasma C26:0 levels, due to endogenous synthesis of these fatty acids. In 1986, the addition of monounsaturated oleic acid reduced the levels and the rate of biosynthesis of saturated VLCFA in cultured skin fibroblasts of patients with ALD. From this, it was found that oral administration of gylceryl trioleate for a period of 3 to 4 months significantly lowered plasma C26:0 levels by approximately 50%. Furthermore, in 1989, Augusto Odone, the founder of Lorenzo’s Oil, added erucic acid to the oil, on the basis of a review of lipid manipulation in animal studies and reports that erucic acid and saturated long-chain fatty acids are elongated by the same microsomal enzyme system. The unsaturated fatty acids in Lorenzo’s Oil competitively compete for chain elongation with saturated fatty acids resulting in reduced endogenous synthesis of VLCFA. This led to the final component in Lorenzo’s Oil, and has been shown to normalize levels of saturated VLCFA and delay the progression of neurologic abnormalities within 4 weeks in most patients.

Lorenzo’s Oil is still popularly used in many ALD patients, but has received inconclusive results within studies. A study conducted by Moser et al. (2005) followed-up 89 asymptomatic boys with X-ALD between the years of 1989 and 2002 that have been treated with Lorenzo’s Oil. The oil was taken orally in a dosage that provided 20% of caloric intake while other fat intake was only limited to 10% to 15% of total calories. Patients were followed up at 6-month intervals. 74% (66) of studied patients were well upon their last follow-up, meaning that they exhibited normal neurological status and normal brain MRI results. Results from the study are shown in the table below after the final follow-up. From this study, it is recommended that Lorenzo’s Oil therapy be offered to male patients with ALD who are neurologically asymptomatic, have normal brain MRI results and are at risk of developing cerebral ALD. Intensive Lorenzo’Oil therapy during the ages at which the risk for cerebral ALD is greatest (boys younger than 7 years) may protect against this phenotype until patients reach ages at which the risk for cerebral ALD diminishes (after 10 years of age).

The administration of Lorenzo’s Oil has only been successful in halting the progression of the disease in patients that are largely asymptomatic, and has limited success in patients that already have neurological abnormalities and are symptomatic. There is evidence that dietary therapy can reduce the levels of VLCFA in the plasma, adipose tissue and liver but no significant reduction is observed in the brain (possibly due to the fact that erucic acid cannot enter the brain at a significant quantity). There is also no evidence of a clinically relevant benefit from dietary treatment with oleic and erucic acids in patients with adrenomyeloneuropathy. Early detection of this disease is crucial in order to obtain the benefits of the oil.

Nevena V.

References:

Moser H, Dubey P, Fatemi A (2004) Progress in X-linked adrenoleukodystrophy. Current opinion in neurology 17(3): 263-269.

Moser H et al. (2005) Follow-up of 89 Asymptomatic Patients With Adrenoleukodystrophy Treated With Lorenzo’s Oil. Archives of Neurology 62: 1073-1080.

Aubourg et al. (1993) A two-year trial of oleic and erucic acids ("Lorenzo's Oil") as treatment for adrenomyeloneuropathy. The New England Journal of Medicine 329(11): 745-752.

Rasmussen M., Moser A., Borel J., Khangoora S., Moser H. (1994) Brain, liver, and adipose tissue erucic and very long chain fatty acid levels in adrenoleukodystrophy patients treated with glyceryl trierucate and trioleate oils (Lorenzo's Oil). Neurochemical Research 19(8): 1073-1082.

Lovastatin as a Treatment for Adrenoleukodystrophy

Lovastatin for X-Linked Adrenoleukodystrophy

 Lovastatin

In a study conducted by Singh et. al they have shown in animal studies that lovastatin can be used as a therapy for adrenoleukodystrophy. Lovastatin is a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor and sodium phenylacetate, which inhibits mevalonate pyrophosphate decarboxylase. This then inhibits the induction of inducible nitric oxide synthase and proinflammatory cytokines involved in the pathogenesis of neurological damage in X-linked adrenoleukodystrophy. For those not in a science major here is some definitions that will help:

-       A 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor is the rate-controlling enzyme of the mevalonate pathway, the metabolic pathway that produce cholesterol

-         Sodium phenylacetate is an aromatic fatty acid, which displays cell growth inhibition, malignant phenotype reduction and cell differentiation

-       A cytokine is a are small cell signaling molecules that are usually produced during an immune reaction

Lovastatin has been shown to increase intracellular cyclic AMP and protein kinase A activity and normalize the levels of very-long chain fatty acids in skin fibroblasts from patients with childhood adrenoleukodystrophy.

The study was conducted by treating patients with 20 mg of lovastatin per day for two weeks, if not side effects occurred the dose was increased to 40 mg a day.  The fatty acids were measured throughout the study to observe the effects. According to their results the plasma levels of very-long chain fatty acids declines in each patient that completed the trial after 6 months.  These results suggested that lovastatin treatment may reduce the very-long chain fatty acids in adults with adrenoleukodystrophy, without any significant side-effects.  The effects of lovastatin are believed to be due to the drug blocking the induction of inflammatory mediators of neurological damage in adrenoleukodystrophy.

A comparative study conducted by Engelen et. al have stated that lovastatin should not be used for a treatment of adrenoleukodystrophy. The conducted their own study where they gave patient with adrenoleukodystrophy a 40 mg dose of lovastatin once daily compared to a placebo dose. The trial was designed to investigate whether lovastatin has a biochemical effect in vivo in patients with X-ALD. They concluded that lovastatin leads to a small decrease in levels of C24:0 and C26:0 in plasma. They also took into account that VLCFAs (very-long-chain fatty acids) are water soluble and therefore only a small amount binds to the albumin in the blood and most bind to the LDL cholesterol.  LDL did not decrease with the lovastatin dose and therefore they considered the results to be nonspecific due to the fact that LDL did not decrease.

With the opposing results of these two studies it is clear that more research is needed to study the effects of lovastatin in patients with adrenoleukodystrophy.  Whether this drug can be used as a therapy is still unclear and more time and resources must be placed on the study of this drug to determine if it holds any positive benefits.

References

Singh, I., Khan, M., Key, L. & Pai, S. 1998, Lovastatin for X-Linked Adrenoleukodystrophy. The New England Journal of Medicine, 339: 702-703

Engelen, M., Ofman, R., Dijkraaf, M., Hijzen, M. & Wardt, L. Lovastatin in X-linked Adrenoleukodystrophy. 2010. The New England Journal of Medicine, 362, 276-277.

Alisha M.