Adrenoleukodystrophy (ALD)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8788425/
The rare, rapidly progressing, neurodegenerative disorder X-linked adrenoleukodystrophy (X-ALD) is caused by a mutation in the ABCD1 gene. As treatment is possible prior to the onset of neurological symptoms, early diagnosis is very important and can be lifesaving. Therefore, X-ALD has been added to newborn screening in various states, this review describes the initial experience of implementing this in Illinois. Over three years there were 276,00 newborns tested, this was done by measuring levels of the X-ALD biomarker C26:0 lysophosphatidylcholine in dried blood spots which is elevated in effected newborns. Samples below the negative cutoff were reported as negative, while samples between the negative and positive cutoff were considered borderline, therefore a second dried blood spot was tested to confirm results. Patients with a positive result were recommended to have follow-up testing where plasma very long fatty-chain acids (VLFCAs) were measured. If elevated the next step was ABCD1 gene sequencing to determine if a genetic variant was detected. The false-positive rate during this screening series was low. Of the 276,000 infants screened, 91 had either an initial positive or borderline result, 33 were referred for diagnostic testing and 17 were diagnosed with X-ALD and 3 with a different peroxisomal disorder. This means that 52% of infants referred for diagnostic testing had a positive diagnosis, depicting the importance of newborn screening for X-linked adrenoleukodystrophy.