Daughter’s Genome Comprises Almost Entirely Father’s Genes
10 JUL 18
Rare Case of Daughter’s Genome Made Up Almost Entirely of Father’s Genes
Usually, we inherit genes from each of our parent in fairly equal measures. However, there are now approximately 20 reported cases of children inheriting almost all of their genes from a single parent. Interestingly, it seems that it is only females that inherit all genes from their father.
There are three ways in which both copies of particular genes or chromosomes can occur in offspring, all are errors in the early stages of embryogenesis:
1. trisomy rescue, in which there is a mitotic loss of one of the three copies of the trisomic chromosome
2. monosomy duplication, in which the lone copy of a chromosome pair is duplicated via non-disjunction
3. gamete complementation, in which a gamete (sperm or egg) that is missing one chromosome unites with a gamete containing two copies of that chromosome by chance
When these mechanisms occur across all 23 chromosomes, a child is born with a genome that is made up almost entirely of a single parent’s genes; a phenomenon termed uniparental diploidy.
However, having two copies of the same gene isn’t always ideal, especially in the case of recessive disorders. This explains why every case reported, except one, has resulted in very high risk of a cancer.
The rare case was reported in the Journal of Human Genetics, in which an 11-year-old girl, who is a genetic “mosaic” of her father, suffers from deafness but with no signs of cancer (so far). Although no cancer has been found, the girl has an extremely high risk of malignancy and is being carefully monitored by a specific outpatient pediatric oncology program.
The study also documented the differences between the percentages of maternal and paternal genes in various tissues. Only about 7% of her blood cells, for example, showed any maternal genes. And 74% of the cells in her saliva held only paternal genes.