Pernicious anemia is often found in conjunction with other autoimmune disorders, suggesting common autoimmune susceptibility genes may be a causative factor. In spite of that, previous family studies and case reports focusing on PA have suggested that there is a tendency of genetic heritance of PA in particular, and close relatives of the PA patients seem to have higher incidence of PA and associated PA conditions. Moreover, it was further indicated that the formation of antibodies to gastric cells was autosomal dominant gene determined, and the presence of antibodies to the gastric cells might not be necessarily related to the occurrence of atrophic gastritis related to PA.

Pathophysiology
Although the healthy body stores three to five years worth of B12 in the liver, the usually undetected autoimmune activity in ones gut over a prolonged period of time leads to B12 depletion and the resulting anemia; pernicious anemia refers to one of the hematologic manifestations of chronic auto-immune gastritis, in which the immune system targets the parietal cells of the stomach or intrinsic factor itself, leading to decreased absorption of vitamin B12. B12 is required by enzymes for two reactions: the conversion of methylmalonyl-CoA to succinyl-CoA, and the conversion of homocysteine to methionine. In the latter reaction, the methyl group of levomefolic acid is transferred to homocysteine to produce tetrahydrofolate and methionine. This reaction is catalyzed by the enzyme methionine synthase with B12 as an essential cofactor. During B12 deficiency, this reaction cannot proceed, which leads to the accumulation of levomefolic acid.
Butenafine, sold under the brand names Lotrimin Ultra, Mentax, and Butop (India), is a synthetic benzylamine antifungal. It is structurally related to synthetic allylamine antifungals such as terbinafine. Medical uses
Butenafine is indicated for the topical treatment of tinea (pityriasis) versicolor due to Malassezia furfur, as well as athletes foot (Tinea pedis), ringworm (Tinea corporis) and jock itch (Tinea cruris) due to Epidermophyton floccosum, Trichophyton mentagrophytes, Trichophyton rubrum, and Trichophyton tonsurans. It also displays superior activity against Candida albicans than terbinafine and naftifine. Butenafine demonstrates low minimum inhibitory concentrations against Cryptococcus and Aspergillus. There is some evidence that it is effective against dermatophyte infections of the toenails, but needs to be applied daily for prolonged periods (at least one year). Typical usage
For 1% cream:

for adults and children 12 years and older:
wash the affected skin with soap and water and dry completely before applying
apply once a day to affected skin for 2 weeks or as directed by a doctor
wash hands after each use
children under 12 years: ask a doctor

Available forms
Butenafine is typically available as a 1% topical cream. Pharmacology
Like the allylamine antifungals, butenafine works by inhibiting the synthesis of ergosterol by inhibiting squalene epoxidase, an enzyme responsible for the creation of sterols needed in fungal cell membranes. Lacking ergosterol, the cell membranes increase in permeability, allowing their contents to leak out. Furthermore, inhibition of squalene epoxidase leads to a toxic buildup of squalene. This double action of butenafine (increased membrane permeability and toxic buildup of squalene) makes butenafine fungicidal rather than merely fungistatic.