Part 1 · The disease
The gene & inheritance
FMF comes from variants in one gene, MEFV, which makes the protein pyrin. Press play to zoom from chromosome 16 down to single amino acids, then tap a variant pin. Below, watch alleles pass from parents to children, and practise reading a genetic report.
Chromosome, band and exon sizes are schematic. Protein domains are drawn at UniProt O15553 coordinates; the hot-spot inset is magnified. Pin colour = current Infevers class.
Animated Punnett square
Each of the four boxes is an equally likely outcome for every pregnancy. "Two variants" means the genotype, not certain illness: penetrance is incomplete.
Pseudodominance. Because carriers are so common, an affected parent often has a carrier partner. Then half the children inherit two variants, and FMF appears in every generation, as if it were dominant. Cazeneuve and colleagues documented this pseudodominant transmission in Armenian families. 33
Read a genetic result
Pick the two alleles a report might list. The tool shows each variant's current Infevers class and how the pair counts in the Eurofever/PRINTO 2019 classification criteria. It is a study aid, not an interpretation of anyone's test. 75,108