Mike Snape, PhD, chief scientific officer at AMO Pharma, talks about diagnosing myotonic dystrophy and its causes.
Transcription:
Just a little bit of background on myotonic dystrophy then. Myotonic dystrophy is a trinucleotide expansion repeat disorder. That means there’s a characteristic stretch of what used to be called junk DNA that is repeated next to a gene called DMPK.
In this condition, that stretch of repeated junk DNA is transcribed to form a repeating junk RNA, and that RNA is present in cells throughout the body and interferes with normal cellular function. Interestingly, in the condition, whenever it’s passed on across the generations, the length of this pathological mutant toxic RNA increases. So each generation is getting a longer and longer version.
As a generalization, the bigger the RNA, the earlier and more severe the presentation of symptoms. By the time you get three or four generations into a family with this, individuals are presenting with symptoms at birth. Characteristically, those affected congenital onset individuals can be very sick unless they have some serious medical intervention, they may not survive the first months of life. They will present with certain cardinal features like a difference in the shape of their mouths, called the tented mouth. They may have club feet and so on and so forth.
One would like to think that a pediatrician seeing a neonatal infant with that facial presentation, those bodily presentations, being very ill would recognize that there’d be a high index of suspicion of this condition, and therefore, order the genetic test and confirm the diagnosis.
Our investigations of the landscape have shown that it doesn’t always work out that way. Some work we commissioned with an independent provider showed that perhaps 25% of children with congenital onset myotonic dystrophy are diagnosed by a cardiologist the child is presenting with heart problems, and then the cardiologist works backwards to determine what it is. I guess what I’m saying is it’s eminently possible to diagnose a congenital myotonic dystrophy infant. The reality is it doesn’t always happen, and perhaps as a society we could do better.
To learn more about myotonic dystrophy and other musculoskeletal disorders, click here: https://checkrare.com/diseases/musculoskeletal-diseases/https://checkrare.com
