Table 1.

Molecular Genetic Testing Used in FOLR1-Related Cerebral Folate Transport Deficiency

Gene 1MethodProportion of Pathogenic Variants 2 Identified by Method
FOLR1 Sequence analysis 3~99% 4
Gene-targeted deletion/duplication analysis 5~1% (rare) 4, 6
1.

See Table A. Genes and Databases for chromosome locus and protein.

2.

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

3.

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

4.

Pope et al [2019] and data derived from the subscription-based professional view of Human Gene Mutation Database [Stenson et al 2020]

5.

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. While exome and genome sequencing may be able to detect deletions/duplications using breakpoint detection or read depth, sensitivity can be lower using these methods than using gene-targeted deletion/duplication analysis.

6.

One intronic variant outside of the exon and the consensus splice junction typically identified by standard sequencing has been reported [Gowda et al 2021].

From: FOLR1-Related Cerebral Folate Transport Deficiency

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