Research Rookies
What are the odds? Chances of inheriting SDHB or SDHD mutation from a parent.
A lay summary of: Davidoff, Lim, Benn et al. (2023). Distortion in transmission of pathogenic SDHB- and SDHD-mutated alleles from parent to offspring. Endocrine-Related Cancer, 30, e220233.
When one parent has a genetic mutation, the odds of their children inheriting that mutation is typically 50/50. These odds are “even” because each parent contributes one copy of that gene to the sperm or egg (the gamete) that will form a fertilized embryo. There’s a 50/50 chance that this copy of the parent’s gene (and therefore the embryo) will have the specific mutation. Thus, if one parent has an SDHB mutation, we normally would expect that, on average, half of that parent’s children would also carry the SDHB mutation and half would not.
Davidoff and colleagues began their study with a surprising observation. A patient with an SDHB mutation had genetic diagnostic testing prior to having a procedure to implant embryos for family planning. The number of embryos with an SDHB mutation was higher than would be expected if the “transmission ratio” was 50/50. Perhaps the assumption of a 50/50 ratio of inheritance for the SDHB mutation was incorrect.
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