Genetics class has shown us
countless examples of inbreeding and consanguinity increasing the risk of
inherited diseases and conditions. Remembering that much of the expression of
our basic DNA is modified by epigenetic factors that are also heritable,
consider the possibility that breastfeeding is a strong regulator of the
epigenome. These epigenetic regulations would be different from each other in
ways that are specific to each breastfeeding mother. Just last month, Ozkan, Tuzun, Kamral and
Duman entertained all of those notions together in an article for the journal
Clinical Epigenetics, thoroughly reviewing the scientific literature for
evidence for or against the “milk kinship hypothesis.”
The strongest piece of evidence
supporting the possibility of milk kinship, according to the paper, is the
presence in breastmilk of microRNA material in exosomes. MiRNAs are responsible for not only
post-trascriptional regulation, but also epigenetic regulators. They perform immunomodulatory funtions, and
there have been 7 miRNA species that are found only in breast milk so far. There are also maternal stem cells in breast
milk, which have been shown to invade deep into the infant tissues from breast milk
ingestion, where they persist for years in mice. The stem cell self-renewal is controlled by
miRNAs.
In times before formula, it was
common for well-off families to hire wet nurses. One wet nurse would often work for several
families in her reproductive lifetime, as well as breastfeeding her own
biological children. It must have been
relatively common in small communities for marriages to occur between people
who were nursed by the same woman, or whose parents were nursed by the same
woman. If the milk kinship hypothesis
bears out, we’ll need to invent a new way to denote epigenetic milk kinship on
our genetic lineage diagrams. (A dotted line with a circle in the middle, maybe?
A single dotted consanguinity line for milk cousins?)
Today, many infants are fed by
hospital breast milk banks that are entirely donated by other mothers. The milk is pasteurized, but Ozkan et al
noted that exosomal miRNA in breast milk can even survive boiling. What might this mean for infants receiving the
donated milk? Ozkan et al ask the right
questions to direct further research to find out.
URL to free full text of the
article: http://www.clinicalepigeneticsjournal.com/content/pdf/1868-7083-4-14.pdf
This is extermely interesting! I never knew that breast milk carried miRNA or that the mother's stem cells got carried through it as well. What I find even more fascinating is the cultural aspect of this as well. I know that many cultures that practice inbreeding ie (1st cousin) marriages prohibit marriages between people who were breast fed by the same women, whether they are related or not. What I know is that it is prohibited by religion...but according to there is probable scientific basis behind it as well. huh...I wonder what sort of affect the infant who are fed from the hospital breast milk banks will have on them?
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