A small number of people suffer from a rare/severe subtype of migraine with aura (MA) called hemiplegic migraine (HM), where weakness or temporary numbness, affects one side of the body, accompanying migraine.
HM is diagnosed/subdivided into:Sporadic hemiplegic migraine (SHM) – no family history of HM exists
Familial hemiplegic migraine (FHM) – 1st or 2nd-degree relative has HM
~0.01% of Europeans suffer HM.
SHM (1/3 of HM cases) results from:
1. Pathogenic-variant newly arisen FHM-genes (listed below)
2. Cellular mosaicism (people with mixtures of cells with completely different genetics)
3. Other gene-transmission-mechanisms
4. Environmental factors
One of 3 specific FHM gene-mutations is passed-down from parents:
1. CACNA1A (FHM type 1) leads a person’s brain cells to miss-handle calcium.
2. ATP1A2 (FHM type 2) leads to altered handling of both sodium, potassium, calcium and possibly acid by brain cells.
3. SCN1A (FHM type 3) leads to altered sodium-handling by brain cells which alters levels neurotransmitter GABA levels.
All mutations, increase risk of brain-cell-hyperexcitability, cortical spreading depression (CSD) and migraine.
No other major HM-causing genes have been found and >75% of genetically tested HM sufferers, have no detectable gene mutation. HM genetic sub-types are indistinguishable although symptom-picture varies widely, even among people with the same genetic mutation.
FHM has:
1. an autosomal dominant inheritance pattern (just one copy of mutated gene can cause disease).
2. a high penetrance – i.e., 70-90% of people with the mutated gene will get migraines.
Nevertheless, penetrance isn’t 100% and twin studies clearly show even identical-twins can have completely different symptom-profiles. Recently, a study concluded that the ‘wide array of symptoms, severity, age of onset and frequency’ suggests that HM-patients getting severe headaches, do so from an unlikely combination of both genetic and endogenous or environmental factors.
Swedish researchers similarly concluded that HM may not be caused by single-gene-mutations; but is likely an extreme-version of migraine with aura, sitting at the severe-end of the HM disease-severity- spectrum.
They argued that a combination of environmental factors working together with rare and/or multiple-common-gene-variants, conspire to produce HM migraines which suggests that even very rare and severe migraine types, have controllable environmental factors, that may significantly lower migraine risk.
Article Written + Submitted by:
Andreas Klein Nutritionist + Remedial Therapist from Beautiful Health + Wellness
P: 0418 166 269