Study Probes Impact of Early-Onset MMD1

Communication difficulties, social role limitations, problems with mobility and walking, and cognitive impairment were the most frequently mentioned themes in open-ended interviews conducted with people affected by congenital-onset or childhood-onset type 1 myotonic muscular dystrophy (MMD1, or DM1) or their parents.

Neurologist Nicholas Johnson and colleagues at the University of Rochester (N.Y.) conducted 34 interviews — 21 with children or adults affected by congenital-onset or childhood-onset MMD1, and 13 with a parent of a child with one of these conditions — to determine what factors most influence quality of life. The researchers published their findings online April 22, 2013, in the Journal of Child Neurology.

Chad Heatwole, a neurologist with a special interest in clinical research at the University of Rochester, received MDA support for his role in this study.

In August 2013, Johnson, now at the University of Utah, received MDA funding for the next phase of these studies. Johnson and colleagues will collect information on how MMD1 symptoms change in children over time.

The goals of this MDA-supported study were:

  • to supply clinically meaningful outcome measures for use in clinical trials of therapies that may improve quality of life in early-onset MMD1; and
  • to guide health care professionals who are caring for patients with this disorder.

In 2012, Heatwole and colleagues published a similar study — also supported by MDA — of the concerns of people with adult-onset MMD1. In that study, they found that hand and arm problems were the most often reported symptoms, and that fatigue, followed closely by mobility impairment, was judged to have the greatest impact on daily life.

These concerns differed from those of the parents and patients in the current study, which is among the first in-depth analysis of the impact of early-onset MMD1 on patients and parents.

About the study

When symptoms occurred at birth, the investigators classified the disorder as congenital MMD1. When symptoms occurred after birth but prior to age 10, they classified it as childhood-onset MMD1.

The 21 children and young adults in the study ranged in age from 9 to 30 years old. Thirteen had congenital MMD1, and eight had childhood-onset MMD1. Affected children and young adults were able to participate to varying degrees, depending on their communication abilities.

Parents of the children and young adults also were interviewed about their perceptions of their children's experiences.

Results

Among children and adults with congenital MMD1 or their parents, the most frequently mentioned themes were:

  • communication difficulties (mentioned 69 times by 13 interviewees); and
  • issues with mobility and ambulation (mentioned 57 times by 40 interviewees).

The most commonly reported individual symptom was difficulty communicating with others. An example of this concern was a parent who said, "She has a great vocabulary, but it's hard, it's hard to understand her. She just runs in that same stream of speech, and she could get off of that and speak more clearly."

Among children and adults with childhood-onset MMD1 or their parents, the themes that represented the most quotes in the interviewed were:

  • cognitive impairment (mentioned 43 times by 29 interviewees); and
  • communication difficulties (mentioned 31 times by four interviewees).

The most common individual symptom reported in this group was hand myotonia — difficulty relaxing one's grip.

When all interviews were combined, the most frequently mentioned themes, in order, were:

  • communication difficulties (mentioned 100 times by 17 interviewees);
  • social role limitations (mentioned 79 times by 54 interviewees);
  • mobility and ambulation [walking ability] (mentioned 74 times by 54 interviewees); and
  • cognitive impairment (mentioned 71 times by 48 interviewees).

Early-onset MMD1 differs from adult-onset MMD1

"As expected, congenital and childhood-onset myotonic dystrophy-associated symptoms are divergent from those of adult-onset myotonic dystrophy type 1," the authors say.

They note that, even where reported symptoms were in the same category — such as cognitive impairment — the details of the concerns were different. Comments of congenital and childhood-onset MMD1 participants focused more on learning difficulties or problems with concentration, while adult-onset MMD1 participants talked more about decreased motivation or memory deficits.

In both the early-onset and the adult-onset study, emotional issues were reported. However, the congenital and childhood-onset MMD1 participants highlighted inflexibility and a narrow scope of interest in life, which were not prominently mentioned by adult-onset MMD1 study participants.

Said one parent of a child with early-onset MMD1: "She says the same thing over and over and over; she sort of disappears into her own little world, so you can't really have a conversation with her, because she just starts spouting something she heard on TV. She is very into her routine. If anything disrupts it, she gets very upset."

Implications for treatment, trials

The investigators say their findings have implications both for future research studies to test experimental treatments for early-onset MMD1 and for the care of patients who have this disorder now.

They say clinicians involved with the care of early-onset MMD1 patients should consider:

  • early intervention with speech therapy to treat communication difficulties;
  • treatments for urinary and fecal incontinence;
  • treatments for fatigue; and
  • treatments for myotonia (inability to relax muscles at will).

They also note that this study supports a potential link between the symptoms of early-onset MMD1 and autism, citing inflexibility, narrow scope of interest, intellectual disability, repetitive speech and inappropriate social responses as examples of features of both disorders. They say patients with congenital or childhood-onset MMD1 may benefit from the same behavioral and psychological therapies used to treat patients with autism.

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