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#apaperaday: Discordant Monozygotic Triplets with Duchenne Muscular Dystrophy

In today’s #apaperaday, Prof. Aartsma-Rus reads and comments on the paper titled: Discordant Monozygotic Triplets with Duchenne Muscular Dystrophy

The pick today is from annals neurology by Wang et al on monozygotic triplets with Duchenne DOI: 10.1002/ana.26966

Authors report 3 Duchenne patients, who are monozygotic triplets (tripletness genetically confirmed) with a deletion of exon 49-52. The patients were first seen at age 8. During follow-up, they lost ambulation at age 10 and from there on progression developed with variability.

MRI showed differences in fat infiltration in the shoulder girdle muscle and also functionally patients showed different ability to lift their arms. There was a correlation between fat infiltration and functional impairment (more fat, more impairment).

The question is of course why there is this difference. It cannot be genetic modifiers as the triplets have the same genetic makeup. Likely it is also not environmental, as they grow up in the same family. Authors conclude that more work is needed.

It is also interesting that lower limb muscle deterioration did seem to be similar for all three – only the upper limbs show differences. Obviously, it will be interesting to learn about respiratory function (not mentioned) and cardiomyopathy (also not mentioned).

So more work and follow-up will be needed – as always. I appreciate the authors flagging these cases and I also appreciate that the patients and family were cooperating in the study as we can learn from this.