Table 1.

Molecular Genetic Testing Used in Familial Hemiplegic Migraine

Gene 1, 2Proportion of FHM Attributed to Pathogenic Variants in GeneProportion of Pathogenic Variants 3 Identified by Method
Sequence
analysis 4		Gene-targeted deletion/duplication analysis 5
ATP1A2 ~10%~99% 61 person 7
CACNA1A 10%-15%~95% 6Multiple families 8
PRRT2 2%-3% 9~75%~25%
SCN1A <1%100% 6None reported
Unknown 1066%-80%NA
1.

Genes are listed in alphabetic order.

2.

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

3.

See Molecular Genetics for information on variants detected in these genes.

4.

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.

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.

6.

Data derived from the subscription-based professional view of Human Gene Mutation Database [Stenson et al 2020]

7.

An intragenic duplication involving exon 21 was reported in one individual with hemiplegic migraine [Gagliardi et al 2017].

8.

A 39.5-kb CACNA1A deletion of the last 16 coding exons was reported in three affected members of one family with episodic ataxia [Riant et al 2008]. CACNA1A rearrangements have also been reported in families with hemiplegic migraine [Labrum et al 2009].

9.
10.

A heterozygous ATP1A4 pathogenic variant was reported in one family; to date, the report has not been confirmed.

From: Familial Hemiplegic Migraine

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