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Understanding ALD

Adrenoleukodystrophy (ALD) is a rare genetic disease that can progress to a serious and life-threatening condition1,2

ALD is a genetic disease caused by mutations in the ABCD1 gene, that results in a deficiency of the peroxisomal protein called adrenoleukodystrophy protein (ALDP). This deficiency leads to the accumulation of very-long chain fatty acids (VLCFAs) in plasma and tissue—primarily of the nervous system and adrenal glands.3

Without early detection, ALD can progress to a serious and life-threatening condition called cerebral ALD.2

DNA with mutations in the ABCD1 gene

DNA with mutations in the ABCD1 gene

ALD primarily affects males1

Because this disorder results from mutations in a gene on the X chromosome, males are more susceptible—it affects approximately 1 in 21,000 males.1 Although ALD primarily affects males, it is possible for females to develop symptoms of the disease in adulthood.3 There is no evidence that the prevalence of ALD varies with ethnicity.3 ALD consists of a spectrum of phenotypes, which may overlap throughout the lifetime of a patient.4 ALD is a genetic disorder, so once it is diagnosed, it’s important to test other family members, as well.1

Even among members of the same family, it is currently not possible to predict the future phenotype of a boy with ALD without monitoring.3

Symptoms of ALD often resemble symptoms of other conditions4,8

Because early symptoms of ALD often resemble those of other medical conditions, such as Addison’s disease, there can be difficulty in differential diagnosis.4,8 Further complicating the diagnosis of ALD, the clinical manifestations of the condition can vary widely, even among members of the same family.1 Adrenal insufficiency is often the first sign of ALD.3,5

Identifying cerebral ALD

ALD can also develop into cerebral ALD, a severe, progressive, and life-threatening neurodegenerative form of the disease. Diagnosing cerebral ALD can be difficult as the cognitive symptoms often resemble those of other conditions, such as attention-deficit/hyperactivity disorder (ADHD), autism or other home and school problems, which can delay diagnosis.3,4 This condition often develops between 3 and 12 years, with most patients ranging from 4 to 7 years of age at the time of symptom onset.9,10

In children, cerebral ALD can lead to:7

  • Behavioral or learning issues
  • Cognitive and neurologic deficits
  • Severe loss of neurologic functions, including impairment of cognition, vision, hearing, and motor function
  • Total disability and death for most patients within 5 years, on average, after the initial onset of symptoms

ALD can progress to cerebral ALD

About 40% of boys with ALD will develop cerebral ALD7

In most patients, cerebral ALD is a rapidly progressing disease that causes progressive behavioral, cognitive, and neurologic deficits and total disability followed by death within 5 years after onset of symptoms.7,9

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