Pmm2 Congenital Disorder of Glycosylation: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 2, 2026.
What kind of doctor treats Pmm2 Congenital Disorder of Glycosylation?
A primary care doctor, such as a pediatrician or family doctor, usually coordinates care. Most children also see a medical geneticist, a specialist in rare inherited conditions. Some see a neurologist or a liver doctor depending on symptoms. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What it is
Pmm2 congenital disorder of glycosylation is a rare genetic condition passed down through genes from both parents. It is named for the PMM2 gene, which helps attach sugars to other molecules, a process called glycosylation. When this process fails, many organs, including the brain, liver, and muscles, can be affected. Most children show signs within the first months of life.
Symptoms
Symptoms vary a lot from one child to another. Many babies have low muscle tone, meaning their muscles feel floppy and weak. Feeding problems, vomiting, and slow weight gain are common in infancy. Some children have developmental delay, sitting, crawling, or walking later than expected. Other signs include a small head, unusual facial features, liver problems, and seizures.
Causes and who gets it
The condition happens when a child inherits one changed copy of the PMM2 gene from each parent. When both parents are carriers, each pregnancy has a one in four chance of being affected. It affects boys and girls equally and is rare.
How doctors diagnose it
Doctors often start by looking at symptoms and medical history. A blood test can measure the activity of an enzyme called phosphomannomutase 2, which is low in this condition. Genetic testing can confirm the diagnosis. A blood test called transferrin testing is often the first step in finding it.
Treatment
There is no cure. Treatment focuses on managing symptoms and preventing problems. Care may include feeding support, physical therapy, speech therapy, and medicines to control seizures if needed. Regular checkups help doctors watch the liver, growth, and development over time.
When to see a doctor
Talk to a doctor if a baby has floppy muscles, trouble feeding, vomiting that does not stop, or is not gaining weight. A doctor should also evaluate a child who is much slower than expected to sit, walk, or talk. Any new or worsening symptoms deserve a prompt medical visit.
How a direct primary care or concierge doctor fits in
A direct primary care doctor is paid with a flat monthly fee instead of billing insurance for each visit. A concierge doctor works similarly but usually charges more and often works alongside insurance. These doctors can manage routine care and coordinate between specialists. But they will refer the child to specialists for diagnosis and treatment of the condition itself.
Common questions
Is Pmm2 congenital disorder of glycosylation curable?
No, there is no cure. Treatment aims to manage symptoms and support development. Outcomes vary widely from one child to another.
Can it be found before birth?
Yes, in some cases. Prenatal testing is testing done during pregnancy. It can find the gene changes if both parents are known carriers. Genetic counseling can help families understand their options.
Do carriers have symptoms?
Usually not. People with only one changed copy of the PMM2 gene typically show no signs of the condition. Symptoms appear when a child inherits two changed copies.
How common is this condition?
It is rare. Estimates suggest it affects roughly one in 20,000 babies. The number may be higher because mild cases can go undiagnosed.
Sources
- NIH Genetic and Rare Diseases Information Center - PMM2-congenital disorder of glycosylation
- MedlinePlus Genetics - PMM2-congenital disorder of glycosylation
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
