Migraine is a common neurological disorder that affects up to 18% of the general population. Familial hemiplegic migraine (FHM) is a rare autosomal dominantly inherited subtype of migraine with aura. In FHM the aura usually consist of a phase with hemiparesis accompanied by typical aura symptoms, including visual, sensory or speech disturbances, followed by a headache phase. Roughly half of the FHM families are linked to chromosome 19p13 (FHM1; CACNA1A), other FHM families are linked to chromosome 1q23 (FHM2; ATP1A2).
The ATP1A2 gene (23 exons) spans ~28 kb of genomic DNA and is located on 1q23, 158.3 Mb from the p-telomere. The CACNA1A gene (49 exons; NM_001127221.1, this transcript lacks exon 32 and 39) spans ~300 kb of genomic DNA and is located chromosome 19p13, 13.2 Mb from the p-telomere. The P348-A2 probemix contains probes for 21 of the 23 exons of the ATP1A2 gene and 17 of the 48 exons of CACNA1A. More probes for CACNA1A can be found in the P279 CACNA1A probemix. In addition, 9 reference probes are included in this probemix, detecting different autosomal chromosomal locations.