Table 1.

Molecular Genetic Testing Used in Fatty Acid Hydroxylase-Associated Neurodegeneration (FAHN)

Gene 1MethodProportion of Pathogenic Variants 2 Detectable by Method
FA2H Sequence analysis 3>95% 4
Gene-targeted deletion/duplication analysis 5See footnote 6.
Uniparental disomy (UPD) analysis 7See footnote 8.

See Molecular Genetics for information on allelic variants detected in this gene.


Sequence analysis detects variants that are benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.


Gene-targeted deletion/duplication analysis detects intragenic deletions or duplications. Methods used may include a range of techniques such as quantitative PCR, long-range PCR, multiplex ligation-dependent probe amplification (MLPA), and a gene-targeted microarray designed to detect single-exon deletions or duplications.


One reported to date [Pierson et al 2012]


Various methods can detect UPD in an apparent FA2H homozygote. Testing may require parental blood specimens.


Four probands from nonconsanguineous families had uniparental disomy (UPD, maternal or paternal) [Soehn et al 2016]. For probands with apparent homozygous FA2H pathogenic variants and no evidence of large gene deletions, parental testing and/or investigation of the proband for UPD are recommended. The presence of UPD will alter recurrence risks (see Genetic Counseling).

From: Fatty Acid Hydroxylase-Associated Neurodegeneration

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