Sialic acid mutation, Chromosome mutation

[DD'eDeN aka note/nickname/alas_my_loves]

.9ma HSA2 fusion 23 paired chromosomes in human, 24 in arboreal great apes
> > >BMC Genomics volume 23, Article number: 616 (2022)
> > >
> > >Abstract
> > >Background
> > >The reduction of the chromosome number from 48 in the Great Apes to 46 in modern humans is thought to result from the end-to-end fusion of two ancestral non-human primate chromosomes forming the human chromosome 2 (HSA2). Genomic signatures of this event are the presence of inverted telomeric repeats at the HSA2 fusion site and a block of degenerate satellite sequences that mark the remnants of the ancestral centromere. It has been estimated that this fusion arose up to 4.5 million years ago (Mya).
> > >
> > >Results
> > >We have developed an enhanced algorithm for the detection and efficient counting of the locally over-represented weak-to-strong (AT to GC) substitutions. By analyzing the enrichment of these substitutions around the fusion site of HSA2 we estimated its formation time at 0.9 Mya with a 95% confidence interval of 0.4-1.5 Mya. Additionally, based on the statistics derived from our algorithm, we have reconstructed the evolutionary distances among the Great Apes (Hominoidea).
> > >
> > >Conclusions
> > >Our results shed light on the HSA2 fusion formation and provide a novel computational alternative for the estimation of the speciation chronology
> > >
> > >https://bmcgenomics.biomedcentral.com/articles/10.1186/s12864-022-08828-7
.
> > >> On a related topic, some AMH's have only 44 chromosomes:
> > >>
> > >> <https://www.thetech.org/ask-a-geneticist/48-46>
> > >
> > >I'm sure a few have other aberrant counts.
> > >
> > >> <https://www.kqed.org/quest/5239/and-then-there-were-44>
> > >>
> > >> <https://www.kqed.org/quest/586/chromosome-fusion-chance-or-design>
> > >
> > >The arboreal Great Apes have a stable 48 and limited largely to tropical swamp forests, AMHs has a stable 46 and has overrun the planet despite serious birthing difficulties, in part due to broad shoulders and big head fitting through a birth canal modified for obligate terrestrial striding bipedalism.
> > ...
> >
> Malaria & ABO blood: Type O protects against worse damage
> Pan & Hs & malaria species:
> - Hs are the only primates missing N-glycolyl neuraminic acid Neu5Gc ;
> - Hs cells are instead rich in N-acetyl neuraminic acid Neu5Ac ;
> - the enzyme that converts Neu5Ac to Neu5Gc is disabled by mutation in Hs.
> The explanation for this loss might be malaria:
> - Pt don't get sick from the Hs malaria parasite Plasmodium falciparum
> (favours Neu5Ac).
> - Hs can't be infected with the Pt parasite Plasm.reichenowi (prefers Neu5Gc
> on Pt RBCs).

I thought the Neu5Ac/Neu5Gc change was unique to humans, but it has happened to a variety of mammals:
https://www.frontiersin.org/articles/10.3389/fimmu.2019.00789/full
Seals, white-tail deer, spider monkeys, weasels, raccoons etc.