. 2020 Jan 31;3(1):e1920356. doi: 10.1001/jamanetworkopen.2019.20356

Table 2. Plasma Very Long-Chain Fatty Acid Confirmatory Test Results for Screen-Positive Cases.

Patient No.	Sex	C26:0, μg/mL	C26:1, μg/mL	C24:0, μg/mL	C22:0, μg/mL^a	C26/C22^b	C24/C22^b	VLCFA Diagnostic Interpretation	Molecular Testing Result	Final Diagnosis
1	M	1.25	0.76	32.48	15.8	0.079	2.05	Increased C26:0, C26:1, C24:0, C24/22, C26/22	1 Hemizygous VUS in ABCD1: c.1522C>T; p.Pro508Ser	X-ALD
8	M	0.95	0.43	31.19	20.6	0.046	1.51	Increased C26:0, C26:1, C24:0, C24/22, C26/22	1 Hemizygous VUS in ABCD1: c.631C>T; p.Leu211Phe	X-ALD
12	M	1.18	0.58	29.13	17.9	0.066	1.63	Increased C26:0, C26:1, C24:0, C24/22, C26/22	1 Hemizygous likely pathogenic in ABCD1: c.1772G>A; p.Arg591Gln	X-ALD
6	F	0.38	0.57	7.76	6.7	0.057	1.16	Increased C26:1, C24/22, C26/22; low C22:0	1 Heterozygous pathogenic in ABCD1: c.1661G>A; p.Arg554His	X-ALD heterozygous female
7	F	0.89	0.64	27.68	18.0	0.050	1.54	Increased C26:0, C26:1, C24/22, C26/22	1 Heterozygous pathogenic in ABCD1: c.1895C>T; p.Thr632Ile	X-ALD heterozygous female
11	F	1.12	0.84	41.37	35.5	0.032	1.17	Increased C26:0, C26:1, C24:0, C24/22, C26/22	Heterozygous deletion exon 7-10 in ABCD1^c	X-ALD heterozygous female
3	F	2.89	2.19	14.90	8.8	0.330	1.70	Increased C26:0, C26:1, C24/22, C26/22	No ABCD1 variants detected; compound heterozygous for pathogenic variants in PEX1 gene^c	Peroxisomal biogenesis disorder
5	F	NA^d	NA^d	NA^d	NA^d	NA^d	NA^d	NA^d	No ABCD1 variants detected; homozygous pathogenic variant in TREX1^d	Aicardi-Goutières syndrome
2	F	0.29	0.23	21.11	24.8	0.012	0.85	Normal	No ABCD1 variants detected	False-positive
9	F	0.19	0.17	17.00	19.9	0.010	0.85	Normal	No ABCD1 variants detected	False-positive
10	F	0.34	0.30	16.12	19.1	0.018	0.84	Normal	No ABCD1 variants detected	False-positive
4	M	0.27	0.22	23.93	20.5	0.013	1.17	Slightly increased C24/C22	1 Hemizygous VUS in ABCD1: c.895C>T; p.His299Tyr	Indeterminate
Reference range^e		0.05-0.41	0.05-0.36	6.87-28.31	8.43-33.51	0.002-0.018	0.64-1.04

Abbreviations: ABCD1, ATP binding cassette subfamily D member 1; C22:0, docosanoic acid; C24:0, tetracosanoic acid; C26:0, hexacosanoic acid; C26:1, 17-hexacosenoic acid; F, female; M, male; NA, not available; PEX1, peroxisomal biogenesis factor 1; TREX1, 3 prime repair exonuclease 1; VLCFA, very long-chain fatty acid; VUS, variant of unknown significance; X-ALD, X-linked adrenoleukodystrophy.

SI conversion factors: To convert micrograms per milliliter to micromoles per liter, multiply by 2.52 for C26:0; by 2.53 for C26:1; by 2.71 for C24:0; by 2.94 for C22:0; by 0.86 for C26:0/C22:0; and by 0.92 for C24:0/C22:0.

^{^a}

Data to more than 1 decimal place were unavailable.

^{^b}

C26/C22 corresponds to C26:0/C22:0, and C24/C22 corresponds to C24:0/C22:0.

^{^c}

Sequencing results were determined from the peroxisomal disorders panel, not from a dried blood spot.

^{^d}

This infant was cared for at another facility; the VLCFAs testing was performed at a different laboratory, and a next-generation sequencing panel, rather than a dried blood spot, determined sequencing results.

^{^e}

Based on reports provided by the referral laboratory; reference range limits are the mean values plus or minus 2 SDs, as defined by the referral laboratory.