Arachnodactyly: Definition, Causes & Treatment

Instructor: Dan Washmuth

Dan has taught college Nutrition and Anatomy courses for over 5 years. He has a B.S. in Exercise Physiology from Furman University and a M.S. in Dietetics & Nutrition from Florida International University. He is a Registered Dietitian (RD) and a Certified Exercise Physiologist (EP-C)

Arachnodactyly is a condition in which the fingers and toes are very long, thin, and sometimes curved. In this lesson, we learn about the definition, causes, and treatment for arachnodactyly.


Rachel is an 18-year-old student who was born with a genetic disorder called Marfan syndrome. Due to this condition, Rachel has developed certain physical abnormalities such as arachnodactyly. Arachnodactyly is a condition in which the fingers and toes are very long, thin, and sometimes curved.

Arachnodactyly results in very long and thin fingers and toes.


Arachnodactyly is associated with several genetic disorders which impact the connective tissues in the body. Connective tissues provide structure to the body and also have a large role in growth and development. Examples of connective tissues include bones, skin, blood, and muscles.

Since connective tissues are involved in the growth process, genetic disorders that impact connective tissues may result in abnormal growth. In the case of arachnodactyly, certain genetic disorders increase the growth and development of the bones in the fingers and toes causing them to become very long and thin. The common genetic disorders associated with arachnodactyly include:

  • Marfan syndrome: This disorder causes the body to produce defective versions of the protein, fibrillin-1, which is involved in the formation of connective tissues. Production of defective fibrillin-1 proteins may result in the abnormal growth and elongation of bones throughout the body, including the bones in the fingers and toes.
  • Homocystinuria: Homocystinuria is a genetic disorder that leads to the accumulation of homocysteine, an amino-acid, in the body. The accumulation of homocysteine can result in disorders of the connective tissues, leading to the development of very long and thin fingers and toes.
  • Ehlers-Danlos syndrome: Ehlers-Danlos syndrome is another genetic disorder that affects the collagen inside the connective tissues throughout the body. Collagen is a protein used to give strength and structure to bones, skin, and other tissues. Collagen is also important for bone growth. Ehlers-Danlos syndrome causes the formation of weak and flexible collagen, which can result in the lengthening of the bones in the fingers and toes.

Additionally, arachnodactyly may occur in a person without any underlying health problems. Some people are just born with very long and thin fingers and toes!

It should be noted that arachnodactyly itself, having long and thin fingers and toes, does not cause any significant health problems. However, the genetic disorders that cause arachnodactyly may cause other abnormalities which may result in significant health problems. For example, Marfan syndrome can also result in the development of an enlarged aorta which can lead to life-threatening heart problems.


Since arachnodactyly is often the result of a genetic disorder that someone is born with, there are no treatments that will cure this condition. As mentioned before, having the long, thin fingers and toes associated with arachnodactyly usually does not cause any severe health problems and most often does not require any treatment.

Sometimes the long fingers of arachnodactyly can make it difficult for a person to perform normal, day-to-day activities such as writing and typing. A physical or occupational therapist can work with a person having these difficulties. A physical or occupational therapist can provide exercises and training to help a person with arachnodactyly cope with any difficult tasks of daily living cause by their long fingers.

Physical or occupational therapy can help a person with arachnodactyly perform daily activities.
physical therapy

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it now
Create an account to start this course today
Used by over 30 million students worldwide
Create an account