Will I develop muscular dystrophy?

December 19, 2015 7:10 AM

I recently had a 23 and Me genetic panel done. Questions about the results of things I have come back positive as...

Two interesting results:

1. I have a "variant" for Nonsyndromic Hearing Loss and Deafness, DFNB1 (GJB2-Related)

I am actually deaf, so it was interesting to find that I have it through my genes. But it says I have only 1 variant, and people need two variants to be deaf. Weird.

2. I have a "variant" for Limb-Girdle Muscular Dystrophy Type 2I.

It also says I need two variants to have this condition as well. I have never heard of anyone in my family having this condition. I have never experienced any symptoms of this (am very athletic), and I am 27.

Reading up on it, it sounds like I would know by know if I had it. Is it possible I will develop muscular dystrophy later in life? I am worried because I am deaf and this testing only shows one variant for the hearing loss gene.

Second, what are ways I can definitely find out? What specialist would be relevant?

posted by anonymous to Health & Fitness (8 answers total)

You need to see a geneticist, or, alternatively, a genetic counselor. You can locate a counselor through the NSGC website.

The way you're describing variants isn't quite right. A genetic counselor would be happy to explain your 23 and Me results, but would probably not rely on those (they're crap...sorry, but they are).

There are a few panels available for hearing loss that they might suggest. There is one done by Elmer-Perkins that has been the standard for the past 15-20 years, but there are newer, better ones available (Otoscope, I think is the name of this).

As far as the limb-girdle thing, that can be a wide-ranging condition (rocker feet, hammer toe, etc.). I would really highly suggest taking the time to discuss these things with a counselor. They have a master's degree and are certified. Most of them are really good at their job and are very good about talking to people about these kinds of things.

Source: have been running the office of a Genetics Division at a hospital for ~10 years. I have no actual medical/counseling training, but you pick up this stuff when you deal with it every day.
posted by kuanes at 7:36 AM on December 19, 2015 [9 favorites]

Informed DNA provides independent telephone/internet based genetic counseling, if there is a not a GC local to you.
posted by beaning at 8:19 AM on December 19, 2015

Nthing to seek genetic counseling. Many hospitals have grant funding and the actual visit with the counselor is free; however, be careful about any actual tests they suggest as the testing is not covered under the grant, is often not covered by insurance, and can be very, very pricey.
posted by charmcityblues at 9:38 AM on December 19, 2015

Yup, talk to someone who knows how to interpret this and someone who's familiar with the specific thing you have. Anecdotally, some types of LGMD can develop later in life (late 30s/early 40s), but go talk to someone.
posted by LobsterMitten at 9:44 AM on December 19, 2015

LGMD2I is one of the autosomal recessive forms of muscular dystrophy that is often late-onset. It can present at an earlier age (teens) or, more commonly, later (forties, fifties). It is sometimes clinically misdiagnosed as Becker Muscular Dystrophy (BMD) because the symptoms and severity and onset can look similar.

Based on the way you are talking about the term "variant," it seems like you are referring to alleles, which would be consistent with the idea that you indeed need two mutated versions of the gene to actually have limb-girdle muscular dystrophy because it is autosomal recessive. If you have only one, you would not develop LGMD2I.

You should talk to a geneticist, preferably somebody who has experience with the muscular dystrophies (this is usually somebody trained in neurology at an academic medical center). She or he will take a detailed family history, possibly do a physical exam, review your results (or order a separate test) and be better equipped to point you in the right direction.
posted by gemutlichkeit at 12:14 PM on December 19, 2015 [2 favorites]

I'd also like to add that insurance companies have become much better about paying for genetic testing. Part of this comes from the Ambry BRCA Supreme Court "patent" decision, and some has come about by the testing becoming more prevalent and cheaper.

Genetic counselors (or their staff/administrators) are often well-versed in the preauthorization process that many insurance companies require. Also, many send-out genetic laboratories will do this heavy lifting for you, nearly guaranteeing a less-than-$200 responsibility on the part of the patient. All this again to say go see a genetic counselor. They will talk about your results, but more importantly give you MORE information, including what kind of testing may be a good idea, what it costs, and how you can keep those costs at a minimum.
posted by kuanes at 6:42 PM on December 19, 2015

Nothing you should see a genetic councelor. That being said: your defness and the one variant for defness may be totally unrelated. You may have an unknown variant in your second gene or the test could have had an error. Do not apply this weird occurrence with defness to the muscular dystrophy genes. We all carry weird genetic variants that don't effect us. It says you need two but you only have one. You're good to go. See a genetic councelor if you're worried or to talk about potential children and risk etc. IMHO, you're totally fine.
posted by Kalmya at 9:19 AM on December 20, 2015

Also, many genetic tests will return a result for "variant of unknown significance" or VUS, which just means that you have a mutated version of a gene which in a different mutation is known to cause whatever it's referring to. So the mutation you have might have no clinical significance, but they note that it's a gene that can cause X.
posted by eglenner at 10:42 PM on December 20, 2015