What is MASS Phenotype?

MASS Phenotype is a connective tissue condition that is similar to Marfan syndrome. It is caused by a similar mutation in the gene called fibrillin-1. Someone with MASS phenotype has a 50 percent chance of passing the gene along to each child.

In MASS Phenotype:

People with MASS Phenotype do not have lens dislocation, but may have myopia, also known as nearsightedness.

You may contact our Help & Resource Center with questions anytime at marfan.org/ask.

MASS Phenotype can be caused by a change in the FBN1 (fibrillin-1) gene, the same gene that causes Marfan syndrome. It can be inherited within families (passed down through generations). It is autosomal dominant, which means that someone with MASS Phenotype has a 50/50 chance of passing the gene to each child. There may be other genes that can cause MASS Phenotype.

MASS Phenotype can only be diagnosed after a comprehensive evaluation by an ophthalmologist, cardiologist, and geneticist (or other doctor) who look for features of a connective tissue condition throughout the body. Both a slit lamp eye exam and an echocardiogram should be done to excludeeye lens dislocation and aortic enlargement, respectively. Echocardiograms should be performed intermittently to exclude emerging Marfan syndrome. Family history is also important. If one individual in the family shows development of an aortic root aneurysm, the diagnosis would change to Marfan syndrome for all affected people in the family.

Is there a genetic test for this gene?Currently, there isn't a gene test that can differentiate MASS Phenotype from Marfan syndrome.

Like Marfan syndrome, MASS Phenotype affects different people in different ways. It is important that the treatment focus on the specific features that are present, regardless of the actual diagnosis.

Always talk to your doctor about your specific needs.

Quality of Life

PhysicalActivity Guidelines

View factsheets, ask a question, even connect with other caregivers to get all the information and support you need to care for someone living with MASS phenotype.

MarfanFoundation

Loeys-Dietz Syndrome Foundation

The VEDS Movement

Join us in the fight for victory over Marfan syndrome, Loeys-Dietz, VEDS, and other genetic aortic and vascular conditions. Help us create a world in which everyone with these conditions can live their best life.

MarfanFoundation

Loeys-Dietz Syndrome Foundation

The VEDS Movement