Congenital Myasthenic Syndromes Blood Test

What is Congenital Myasthenic Syndromes?

Congenital Myasthenic Syndromes (CMS) are rare inherited disorders that affect the neuromuscular junction, causing progressive muscle weakness and fatigue. They are caused by genetic mutations affecting proteins at the neuromuscular junction where nerves communicate with muscles. The MuSK and LRP4 Antibodies Panel is the most important test for CMS because it helps differentiate between inherited congenital forms and acquired myasthenia gravis.

RECOMMENDED TEST MuSK and LRP4 Antibodies Panel
Google reviews 505 reviews
$7,400 $5,772
What's included
Fast & easy, results by email & SMS
No extra fees paid at the lab
No need to visit a doctor
Private & confidential
No insurance needed
Results explained
Why Private MD Labs?
90-day money-back guarantee Lab order in minutes Save a trip to the doctor Low prices since 2005 Labs within 2 miles

What causes Congenital Myasthenic Syndromes?

Congenital Myasthenic Syndromes are caused by genetic mutations that affect proteins at the neuromuscular junction where nerve signals trigger muscle contractions. These mutations can affect various proteins including acetylcholine receptors, acetylcholinesterase, choline acetyltransferase, and other proteins essential for neuromuscular transmission. Unlike acquired myasthenia gravis which is an autoimmune disorder, CMS is inherited and symptoms typically appear in infancy or early childhood, though some forms may not become apparent until adulthood.

What is the best test for Congenital Myasthenic Syndromes?

The MuSK and LRP4 Antibodies Panel is the most important blood test for Congenital Myasthenic Syndromes because it helps distinguish between inherited CMS and acquired myasthenia gravis by detecting antibodies against muscle-specific kinase and low-density lipoprotein receptor-related protein 4. The Myasthenia Gravis Panel 3 is also essential as it screens for various antibodies that, when negative, support a CMS diagnosis rather than an autoimmune condition. However, genetic testing remains the gold standard for definitively diagnosing CMS by identifying the specific gene mutations responsible for the condition.

When should I get tested for Congenital Myasthenic Syndromes?

You should get tested if you experience progressive muscle weakness that worsens with physical activity and improves with rest, especially if symptoms began in childhood or you have a family history of neuromuscular disorders. Testing is also important if you notice drooping eyelids, double vision, difficulty swallowing or chewing, weakness in your arms and legs, or if your baby has feeding difficulties and weak cry. Early testing is critical because CMS symptoms can worsen over time and proper diagnosis ensures you receive the correct treatment, as medications used for acquired myasthenia gravis may not work or could even worsen some forms of CMS.

What are the symptoms of Congenital Myasthenic Syndromes?
Symptoms of Congenital Myasthenic Syndromes include muscle weakness that worsens with activity and improves with rest, drooping eyelids (ptosis), double vision, difficulty swallowing and chewing, weak facial muscles, and limb weakness affecting arms and legs. Infants with CMS may have a weak cry, feeding difficulties, delayed motor milestones, and episodes where breathing becomes difficult. The severity and specific symptoms vary depending on which genetic mutation is present, with some people experiencing only mild eye muscle weakness while others have severe generalized muscle weakness affecting breathing and mobility.
Who is at risk for Congenital Myasthenic Syndromes?
People with a family history of Congenital Myasthenic Syndromes are at highest risk since these disorders are inherited through genetic mutations passed from parents to children. The inheritance pattern varies depending on the specific gene involved, with most forms inherited in an autosomal recessive pattern requiring both parents to carry the mutated gene. Consanguineous marriages (between close relatives) increase the risk of recessive genetic disorders including CMS. Anyone with unexplained muscle weakness beginning in infancy, childhood, or even adulthood should be evaluated, especially if they have relatives with similar symptoms or diagnosed neuromuscular disorders.
What happens if Congenital Myasthenic Syndromes is left untreated?
Untreated Congenital Myasthenic Syndromes can lead to progressive muscle weakness that significantly impacts quality of life and may become life-threatening if respiratory muscles are affected. Without proper management, you may experience increasing difficulty with daily activities like walking, eating, and speaking, as well as dangerous complications including aspiration pneumonia from swallowing difficulties and respiratory failure. Some forms of CMS can cause episodes of severe muscle weakness called myasthenic crises that require emergency medical attention. Early diagnosis and treatment are essential because specific medications can significantly improve muscle strength and prevent complications, though the wrong medications can actually worsen certain types of CMS.
Can Congenital Myasthenic Syndromes be diagnosed with a blood test?
Blood tests alone cannot diagnose Congenital Myasthenic Syndromes, but they play a crucial supportive role in the diagnostic process by ruling out acquired myasthenia gravis, which presents with similar symptoms. The MuSK and LRP4 Antibodies Panel and Myasthenia Gravis Panel 3 help distinguish between autoimmune and inherited causes of muscle weakness. Definitive diagnosis requires genetic testing to identify the specific gene mutations responsible for CMS, along with clinical evaluation, electromyography (EMG) studies, and sometimes muscle or nerve biopsies to assess neuromuscular junction function.
How is Congenital Myasthenic Syndromes treated?
Treatment for Congenital Myasthenic Syndromes varies depending on the specific genetic mutation and must be carefully tailored because medications that help some forms can worsen others. Acetylcholinesterase inhibitors like pyridostigmine improve muscle strength in many CMS types by increasing acetylcholine availability at the neuromuscular junction. Some patients benefit from 3,4-diaminopyridine which enhances nerve signal transmission, while certain CMS forms respond to ephedrine or albuterol. Unlike acquired myasthenia gravis, immunosuppressive medications are not used for CMS since it is not an autoimmune condition, and proper genetic diagnosis is essential to avoid potentially harmful treatments.
How can I prevent Congenital Myasthenic Syndromes?
Congenital Myasthenic Syndromes cannot be prevented since they are caused by inherited genetic mutations present from birth. However, genetic counseling is valuable for families with a history of CMS to understand inheritance patterns and assess the risk of passing the condition to children. If both parents are known carriers of a CMS-causing gene mutation, preimplantation genetic diagnosis (PGD) during in vitro fertilization can identify embryos without the mutations. Early diagnosis and treatment can prevent complications and improve quality of life, so families with a history of CMS should ensure children are monitored for symptoms and tested promptly if muscle weakness develops.
What can I do at home for Congenital Myasthenic Syndromes?
At home, you can manage Congenital Myasthenic Syndromes by pacing activities to avoid muscle fatigue, taking frequent rest breaks throughout the day, and scheduling important tasks during times when your muscle strength is strongest. Maintain good nutrition with adequate protein and calories to support muscle health, and stay well-hydrated to optimize overall body function. Avoid extreme temperatures, infections, and medications that can worsen muscle weakness such as certain antibiotics, beta-blockers, and magnesium supplements. Work with physical and occupational therapists to learn exercises that maintain mobility without overexertion, and use assistive devices when needed to conserve energy and prevent falls while managing daily activities safely.
How’s this work?
Getting your blood test with us is easy, private & backed by the power of science.

Long story short:
  1. In the test options, use the filters or search box to narrow your choices and find the test you want.
  2. If you need a hand navigating through options, text our super friendly support team at 754-799-7833, and we'll provide tailored suggestions to help you find the ideal test.
  3. Once your order is placed, we’ll create your doctor’s lab order remotely, without any need for you to make a trip to a doctor in person or to talk to the doctor. Expect to receive your doctor’s lab order right in your inbox. It will also be in your patient portal if you need to find it later. We’ll also include instructions regarding fasting and other requirements for your test. Your patient portal will be auto-created hassle-free during checkout.
  4. If this is your first time ordering, you'll be prompted to create a password for instant login access to your patient portal. It's a quick way to conveniently access your orders and results whenever you want.
  5. When you’re ready, visit one of our 4,000 locations. Just bring your ID – no printing or faxing of your lab order is needed, as your order and details will already be in the lab system.
  6. Note that most lab locations don’t accept walk-ins, so it’s best to book an appointment in advance. Don’t worry – we’ll provide detailed instructions along the way.
  7. You’ll get your results via email & SMS and dive into understanding your body better. Yup, that easy!
  8. If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.
How do I know which test to get?
In the test options, find the test you want. If you’re not sure which test to get, we can lend a hand in finding the right option.

Just text or call us at 754-799-7833, email us at support@privatemdlabs.com, and we'll gladly help you. We've got your back and reply quickly.
Is it possible to make changes to my lab order if I made a mistake with the name, date of birth, or any other details?
Absolutely! We totally understand that errors can happen. No worries, we're here to help you.

Just reach out to us via text at 754-799-7833 or shoot us an email at support@privatemdlabs.com. Remember to include your order number and let us know the correct information you’d like to update. Our awesome team will jump right in and make sure everything is sorted out and accurate for you.

There are no changes necessary if your address is wrong on the requisition though. We don’t mail anything out.

Our lab requires an address to be listed to generate an order.
Do you accept health insurance?
Only HSA & FSA is accepted.

Our services are strictly self-pay and cannot be submitted to your health insurance provider except for Health Savings Accounts or Flexible Savings Accounts.

This policy applies to all insurance companies, including federal health insurance programs like Medicare.

If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com.
Can I cancel my order?
Yes.

We get it – sometimes your needs change.

As long as your samples haven’t been collected yet, we’re happy to help you cancel your order.

If you have any further questions, please text us at 754-799-7833 or email support@privatemdlabs.com.

You can read more about our cancellation policy here.
How can I find a lab location near me?
During the ordering process, you’ll be able to select a specific lab near you, with no strings attached! You can switch it up later easily and visit any of our authorized locations as long as it’s the same lab company you selected your test for (Quest Diagnostics or Labcorp).

Before you proceed with your order, feel free to browse through all our lab locations here. This will give you the peace of mind of knowing that there's a lab nearby your home, office or your favorite gym.

If you have any questions, please text us at 754-799-7833 or email support@privatemdlabs.com and we'll gladly help you.
Here’s how easy it is to get blood work done on your terms
Choose a checkup
Order your test Save a trip to the doctor. Your results will come with clear, friendly explanations. Takes 2 minutes
Book a lab
Book an appointment Visit any of our 4,000 nearby lab locations to have your samples collected. Book or walk-in
Choose a checkup
Get results Receive a clear, easy-to-digest health report by email & SMS within a few business days. Get answers, fast

Here’s why 1,000,000+ customers chose us for affordable hassle-free private blood testing.

You get clinical lab reports & simplified health insights.
Save time & gas, go straight to the lab. Our doctors cover the rest.
Results start landing the next day after your lab visit.*
We don’t sell or share your data. Your time & privacy matter.
US-licensed doctors have your back if things get unclear.
No hidden fees, nice discounts for regular checkups.
Save a trip to the doctor, go directly to the lab
Instant orders, results often overnight*
Results explained in simple language
Reviewed by US licensed doctors
Fast & confidential, we never sell or share your data
No insurance needed, transparent pricing
Demo results
Testosterone 375 ng/dL
Demo results
Normal Optimal 400 - 1000 High
375 ng/dL

What this means

Your testosterone levels are slightly below the optimal range. While this is not necessarily cause for concern, it may contribute to occasional fatigue, reduced motivation, or lower muscle mass over time.

* Regular blood test results (e.g., CBC) typically start arriving the next business day after sample collection. More complex tests, such as hormone panels, may take up to 10–15 business days due to their complexity.

Us vs. Them

Not overhyped or overpriced. Just comprehensive blood testing made simple and for everyone.

* Regular blood test results (e.g., CBC) typically start arriving the next business day after sample collection. More complex tests, such as hormone panels, may take up to 10–15 business days due to their complexity.

1,000,000+ blood tests later, here's what our customers say

Google reviews 505 reviews Next
MuSK and LRP4 Antibodies Panel
Google reviews 505 reviews
$7,400 $5,772
What's included
Fast & easy, results by email & SMS
No need to visit a doctor
Private & confidential
No insurance needed
Results explained
No extra fees paid at the lab

Sample results

Sample image
For you & your coach Health insights Written in human language, backed by science.
Sample image
For you & your doc Classic lab report A familiar and comprehensive lab report.

Ask AI

Your 24/7 Lab Guide

Quick questions:

Which test is right for my symptoms?
What could be causing this?
When should I get tested?
A
Hi, I'm AI. I can help you find the right test, explain results, or prepare for your visit. What can I help with?
Just now
A
AI provides insights, not medical diagnoses.