Preferential allele amplification leading to RyR1 misgenotyping in a malignant hyperthermia susceptible individual

Background Many current methods for the detection of gene variants relevant for inherited disorders like malignant hyperthermia (MH) rely on the polymerase chain reaction (PCR). A positive PCR result for the genetic region of interest is required for downstream analysis like sequencing, restriction digestion or probe hybridization. However, it is sometimes overlooked that in order to obtain a true genotype, both paternal and maternal alleles must be represented in the PCR product. We present the case of a preferential PCR amplification of one ryanodine receptor subtype 1 (RyR1) mutant allele that led to apparent homozygosity of a proband.