Mucolipidosis IV (ML4) Screening
Mucolipidosis IV, or ML4, is a rare inherited condition that affects development, vision, and digestion beginning in infancy. It’s caused by mutations in the MCOLN1 gene. People of Ashkenazi Jewish descent are much more likely than the general population to carry one of these genetic mutations. Carriers have no symptoms, so most families don’t know they're at risk until a child is affected. A carrier screen for Mucolipidosis IV checks for the genetic mutation ahead of time, so you can understand your risk before you begin planning a pregnancy.
What Is Mucolipidosis IV?
Mucolipidosis IV belongs to a group of conditions called lysosomal storage disorders. In ML4, cells can’t properly move certain materials to and from lysosomes, the cell's recycling centers.² One sign that sets ML4 apart from similar conditions is achlorhydria, which means the stomach makes little or no acid. As a result, levels of a hormone called gastrin in the blood rise sharply.¹
Infants with ML4 typically have weak muscle tone and are slow to reach motor milestones. Many also have clouding of the cornea, the clear front layer of the eye. These early signs are sometimes first mistaken for cerebral palsy.1 About 95% of people with ML4 have this typical, more severe form. The other 5% have an atypical form with milder effects on movement and thinking, but they still develop progressive vision loss and achlorhydria.¹
Vision loss in ML4 gets worse over time. Breakdown of the retina leads to severe vision loss in nearly all affected people by their early teens.¹ Between ages 10 and 20, the condition’s effects on the nervous system become clearer. Most people develop increasing muscle stiffness (spasticity) and lose motor skills they had already gained.1 Kidney failure, recognized as a feature of ML4 only in recent years, can also develop later in life.¹
There are no treatment guidelines for Muculipidosis IV yet , so care focuses on managing symptoms as they arise.¹ Most people with the typical form live into adulthood, though life expectancy can be shorter depending on the severity of neurologic disability or kidney failure.¹
MCOLN1
MCOLN1 is the gene associated with ML4. It gives instructions for making a protein called mucolipin-1, which sits on the surface of lysosomes.² Mucolipin-1 helps move materials between lysosomes and other parts of the cell.² When MCOLN1 doesn't work properly, this movement breaks down and material builds up inside cells throughout the body. This buildup leads to the condition’s effects on the nervous system, eyes, and digestion. ²
Like most genes, everyone has two copies of MCOLN1, one inherited from each parent. A person with one working copy and one non-working copy is called a carrier. Carriers don’t have symptoms, because one working copy is enough. ML4 only develops when a person inherits a nonworking copy from both parents.
Mucolipidosis IV is inherited in an autosomal recessive pattern.¹ If both parents are carriers, each pregnancy has:
- A 25% chance the child inherits a non-working copy from each parent and is affected by Mucolipidosis IV
- A 50% chance the child is an unaffected carrier, like the parents
- A 25% chance the child inherits two working copies and is not a carrier
Why Mucolipidosis IV Carrier Screening Matters
Carriers of Mucolipidosis IV have no symptoms, so screening is the only reliable way to know your carrier status. That’s why ML4 is included on most expanded carrier screening panels. The American College of Medical Genetics and Genomics (ACMG) recommends offering carrier screening for ML4 to everyone who is pregnant or planning a pregnancy, not only people with a known family history.
Your Odds of Carrying the MCOLN1 Gene Change
Mucolipidosis IV is strongly linked to Ashkenazi Jewish ancestry. , About 1 in 100 to 1 in 127 people of Ashkenazi Jewish descent are carriers.¹ More than 80% of people diagnosed with Mucolipidosis IV, including both typical and atypical cases, have Ashkenazi Jewish ancestry.² Outside this population, the condition is very rare with only a small number of cases reported worldwide.1 Because carriers have no symptoms, ancestry is often a more reliable reason to get screened than family history.
Who Should Consider Screening
Mucolipidosis IV screening may be especially helpful if any of these apply to you:
Ashkenazi Jewish Ancestry
The carrier rate in this population is high enough that ancestry alone is often reason to get screened, regardless of family history.¹ ML4 is one of several Ashkenazi Jewish genetic diseases with a higher carrier rate in this community.
Planning a Pregnancy
If you’re planning a pregnancy, screening ahead of time gives you the most information and the widest range of options before you conceive.
A Partner Who Has Already Screened Positive
If your partner has already screened positive for a change in MCOLN1, you'll need to know your own carrier status to understand whether your child could be at risk.
Using a Sperm or Egg Donor
If you’re using an egg or sperm donor, their carrier status matters just as much as a partner’s would. Your child will inherit one copy of each gene from the donor, so a donor who carries a change in the same gene as you creates the same risk.
Family History of Unexplained Developmental Delay or Early Vision Loss
If Mucolipidosis IV runs in your family, your chance of being a carrier is higher than average. ML4 is also sometimes first mistaken for cerebral palsy or an eye condition.¹ If a relative had unexplained developmental delay or lost skills, along with early corneal clouding or vision loss, mention it to a genetic counselor, especially if they never had a confirmed diagnosis.¹
How At-Home Genetic Testing Works
Order and register
Collect your sample
Return your sample
Get your results
Talk to a genetic counselor
Costs and Insurance Coverage
Insurance Billing
Self-Pay Option
Understanding Your Results
Positive (Carrier)
A positive result means you carry one working copy and one nonworking copy of MCOLN1. You are not affected by Mucolipidosis and never will be, but you can pass the nonworking copy of the gene to a child. It is critical to have your partner tested, as the risk of having an affected child is impacted by whether they carry a change in the same gene too. This also applies if you're using a sperm or egg donor.
Negative Result
A negative result means there is no detectable mutation in your MCOLN1 gene and that there is a very low chance of being a carrier for Mucolipidosis.
If You and Your Partner Are Both Carriers
If both partners carry a change in MCOLN1, each pregnancy has a 25% chance of being affected by Mucolipidosis.1,2 A genetic counselor will review your options for family planning, including prenatal testing during a pregnancy, using assisted reproductive options to help avoid having an affected child, or choosing not to have biological children together. If you are already pregnant, diagnostic tests such as chorionic villus sampling or amniocentesis can determine whether a current pregnancy is affected, giving you an answer before birth rather than waiting until delivery.
Know Your Risk Ahead of Time
Frequently Asked Questions
What Is Mucolipidosis IV Genetic Testing?
Reproductive carrier screening looks for changes in MCOLN1, the gene responsible for Mucolipidosis IV. Carrier screening tells you whether you carry one copy of the disease-causing genetic mutation. Because carriers have no symptoms, carrier screening is especially useful before pregnancy. For a full walkthrough of the process, see our complete guide to carrier screening.
How Does Mucolipidosis IV Inheritance Work?
Mucolipidosis IV follows an autosomal recessive pattern. This means a child must inherit a changed copy of MCOLN1 from both parents to be affected. When both parents are carriers, each pregnancy has:
- A 25% chance of the child being affected
- A 50% chance of the child being an unaffected carrier
- A 25% chance of the child inheriting two working copies
How Common Is Mucolipidosis IV Among Ashkenazi Jews?
About 1 in 100 to 1 in 127 people of Ashkenazi Jewish descent carry one of the two genetic mutations most commonly linked to Mucolipidosis IV in this population.¹ More than 80% of people diagnosed with the condition have Ashkenazi Jewish ancestry.²
What Causes the Digestive Symptoms in Mucolipidosis IV?
Mucolipidosis IV disrupts a channel that certain stomach cells need to release acid. As a result, the stomach makes little to no acid, a condition called achlorhydria. This causes a sharp rise in blood levels of the hormone gastrin. This rise is distinctive enough to help confirm a diagnosis alongside genetic testing.¹
Can Mucolipidosis IV Cause Kidney Problems?
Yes. Progressive kidney failure has been recognized in recent years as a feature of typical Mucolipidosis IV, and it can develop later in life.¹
Is There a Prenatal Test for Mucolipidosis IV?
Yes. If you're already pregnant and both partners are found to be carriers, diagnostic testing such as chorionic villus sampling or amniocentesis can determine whether the pregnancy is affected.³
Is Genetic Testing for Mucolipidosis IV Covered by Insurance?
Most commercial insurance plans cover genetic testing for Mucolipidosis IV as part of a broader carrier screening panel, especially for people with Ashkenazi Jewish heritage. Your exact cost depends on your plan, deductible, and copay. Once you register, your jscreen care navigator will work with you on any questions you may have about your specific plan. Many people pay $0 out of pocket for the lab test.
References
- Misko A, Grishchuk Y, Goldin E, Schiffmann R. Mucolipidosis IV. GeneReviews. University of Washington, Seattle. Initial posting January 28, 2005. Updated February 11, 2021. Accessed September 24, 2026. https://www.ncbi.nlm.nih.gov/books/NBK1214/
- Mucolipidosis IV; ML4. Online Mendelian Inheritance in Man (OMIM). Johns Hopkins University. Entry #252650. Created June 4, 1986. Last edited May 9, 2024. Accessed September 24, 2026.
https://www.omim.org/entry/252650 - Chorionic Villus Sampling (CVS). Cleveland Clinic. Last reviewed August 8, 2024. Accessed September 24, 2026.
https://my.clevelandclinic.org/health/diagnostics/4028-chorionic-villus-sampling-for-prenatal-diagnosis