X-Linked Adrenoleukodystrophy Testing

See Testing Strategy

Very Long-Chain and Branched-Chain Fatty Acids Profile 2004250
Method: Liquid Chromatography-Tandem Mass Spectrometry

Biochemical test to measure concentration of very long-chain fatty acids (VLCFAs) C22-C26, pristanic acid, and phytanic acid

Initial test to screen for disorders of peroxisomal biogenesis and/or function, including X-ALD and Zellweger syndrome

Confirmatory test for abnormal newborn screening suggestive of X-ALD

Adrenoleukodystrophy, X-Linked (ABCD1) Sequencing and Deletion/Duplication 2011906
Method: Polymerase Chain Reaction/Sequencing/Multiplex Ligation-dependent Probe Amplification

Preferred molecular test to:

  • Confirm diagnosis of X-ALD following abnormal results from VLCFA profile test
  • Determine carrier status in females when familial variant is unknown

Detect most pathogenic variants

Adrenoleukodystrophy, X- Linked (ABCD1) Sequencing 2011902
Method: Polymerase Chain Reaction/Sequencing

Useful molecular test to confirm diagnosis or carrier status for X-ALD

Detects most pathogenic variants

Sequencing does not detect deletions and duplications

Related Test
Familial Mutation, Targeted Sequencing 2001961
Method: Polymerase Chain Reaction/Sequencing

Useful when a pathogenic familial variant identifiable by sequencing is known

X-linked adrenoleukodystrophy (X-ALD) is a rare X-linked metabolic disorder caused by variants in the ABCD1 gene that cause a deficiency in adrenoleukodystrophy protein (ALDP) and subsequent accumulation of very long-chain fatty acids (VLCFAs). VLCFA accumulation occurs in plasma and all tissue types, but primarily affects the adrenal cortex and white matter of the brain and spinal cord, resulting in a range of clinical outcomes.

Adrenal insufficiency may be the initial presentation of X-ALD, and 21-hydroxylase antibody testing may confirm or exclude an autoimmune etiology. In X-ALD, 21-hydroxylase antibody testing results will be normal; therefore, males with adrenal insufficiency and normal 21-hydroxylase antibody testing should be tested for X-ALD (VLCFA profile).

Testing Strategy

Diagnostic Testing

  • VLCFA and branched-chain fatty acid (BCFA) profile is the first-line test for an individual with suspected X-ALD or adrenomyeloneuropathy
  • Molecular testing (ABCD1) is recommended for diagnostic confirmation in individuals with clinical and/or biochemical presentation of X-ALD

Disease Overview


1/14,700 live births 





ABCD1 gene, contains 10 exons 




Neurologic symptoms are present in nearly 100% of males by adulthood.


  • Most are specific to a particular family (“private variants”)
  • ~4-19%of individuals with X-ALD have a de novo variant 

For more information on the disease including testing strategy, disease overview, and genetics, visit the X-Linked Adrenoleukodystrophy topic in ARUP Consult®.

Test Interpretation

Biochemical testing (VLCFAs and BCFAs)

  • Elevated VLCFAs in males
  • ~85% of heterozygous female carriers will have elevated VLCFAs 

Molecular testing (ABCD1)


  • Clinical sensitivity
    • Sequencing of ABCD1: ~97% 
    • Deletion/duplication of ABCD1: ~3% 
  • Analytical sensitivity/specificity: 99%


  • Positive
    • Pathogenic variant detected
    • Confirms X-ALD in males and carrier status in females
  • Negative
    • No variant detected
    • X-ALD is less likely but not excluded
  • Inconclusive: variants of unknown clinical significance may be identified


  • Exons 7-10 are not evaluated by deletion/duplication analysis due to the presence of pseudogenes
  • Breakpoints of large deletions/duplications will not be determined
  • Diagnostic errors can occur due to rare sequence variations
  • Variants in genes other than ABCD1, regulatory region variants, and deep intronic variants are not evaluated
  1. Huffnagel IC, Dijkgraaf MG, Janssens GE, van Weeghel M, van Geel BM, Poll-The BT, Kemp S, Engelen M. Disease progression in women with X-linked adrenoleukodystrophy is slow. Orphanet J Rare Dis. 2019; 14(1): 30. PubMed
  2. Kemp S, Berger J, Aubourg P. X-linked adrenoleukodystrophy: clinical, metabolic, genetic and pathophysiological aspects. Biochim Biophys Acta. 2012; 1822(9): 1465-74. PubMed
  3. Wiesinger C, Eichler FS, Berger J. The genetic landscape of X-linked adrenoleukodystrophy: inheritance, mutations, modifier genes, and diagnosis. Appl Clin Genet. 2015; 8: 109-21. PubMed
  4. Raymond G, Moser A, Fatemi A. X-Linked Adrenoleukodystrophy. In: Adam MP, Ardinger HH, Pagon RA, Wallace SE, editors. GeneReviews, University of Washington, 1993-2019. Seattle, WA [Updated: Feb 2018; Accessed: Jul 2019]
  5. Bornstein SR, Allolio B, Arlt W, Barthel A, Don-Wauchope A, Hammer GD, Husebye ES, Merke DP, Murad H, Stratakis CA, Torpy DJ. Diagnosis and Treatment of Primary Adrenal Insufficiency: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2016; 101(2): 364-89. PubMed

Last Update: June 2019