LIke ThisLIke ThisLIke ThisLIke ThisLIke This

c16 FEOM3 is the third genetic locus for CFEOM that our laboratory identified. This locus was identified using the technique of linkage analysis. The FEOM3 locus is at the telomere of the long arm of human chromosome 16 (16qter), as shown in the schematic to the left. The critical region for the FEOM3 disease gene is flanked by the polymorphic marker D16S498 to 16qter.

Thus far, two families have been identified that are linked to the FEOM3 locus. These families were studied in collaboration with Dr. Edward Doherty and his colleagues in New Brunswick, Canada1, and Dr David Mackey from The Royal Hobart Hospital in Tasmania, Australia2. The disorder in these families is a form of non-classic CFEOM. The disorder exhibits dominant inheritance but is variably expressed in affected individuals and may skip a generation (incomplete penetrance), as was found in the family enrolled through Dr Doherty.

In the two CFEOM3 families we have identified, there is marked variability of clinical phenotype. Severely affected individuals are born with bilateral ptosis, with their eyes fixed in a downward and outward position, and with marked restriction of movement in both eyes. Forced duction testing is positive for restriction. This 'severe' phenotype is demonstrated by the photographs right, bottom most. in which the individual is looking straight on, up, down and to either side. Mildly affected individuals have normally positioned eyes but a limitation of vertical (upward) gaze, as demonstrated by the photographs of the family member right, uppermost. Moderately affected individuals have asymmetrical involvement with one eye severely and one eye mildly affected.

We now know the genetic basis of CFEOM3, mutations in the TUBB3 gene encoding component of microtubules, a neuronal specific tubulin. Please click on the press release links at the top of the page for details. The diagram below details the pathology for CFEOM3 demonstrating a variable absence of the entire cranial nerve III oculomotor unit, affecting the superior branch to a greater extent than the inferior branch, absence of the corresponding oculomotor subnuclei in the midbrain, and variable abnormalities of the superior rectus, inferior rectus, medial rectus, inferior oblique, and levator muscles. (Refer to eye muscle and nerve anatomy to review the normal lateral eye).


CFEOM3 Proposed Pathology 

Please contact Caroline Andrews to obtain further information on the genetic studies that we are undertaking and if you are interested in enrolling a patient or participating yourself.


Online Mendelian Inheritance in Man (OMIM). Victor A. McKusick, Editor, Johns Hopkins University, last updated 3/17/2004 (entry number #600638). Home page:

  • Doherty EJ, Macy ME, Wang SM, Dykeman CP, Melanson MT, Engle EC. CFEOM3: a new extraocular congenital fibrosis syndrome that maps to 16q24.2-q24.3. Invest Ophthalmol Vis Sci. 1999 Jul;40(8):1687-94. http://
  • Mackey DA, Chan WM, Chan C, Gillies WE, Brooks AM, O'Day J, Engle EC. Congenital fibrosis of the vertically acting extraocular muscles maps to the FEOM3 locus. Hum Genet. 2002 May;110(5):510-2. Epub 2002 Mar 23.
Request an Appointment

If this is a medical emergency, please dial 9-1-1. This form should not be used in an emergency.

Patient Information
Date of Birth:
Contact Information
Appointment Details
Send RequestIf you do not see the specialty you are looking for, please call us at: 617-355-6000.International visitors should call International Health Services at +1-617-355-5209.
Please complete all required fields

This department is currently not accepting appointment requests online. Please call us at: 617-355-6000. International +1-617-355-6000.

This department is currently not accepting appointment requests online. Please call us at: 617-355-6000. International +1-617-355-6000.

Thank you.

Your request has been successfully submitted

You will be contacted within 1 business day.

If you have questions or would like more information, please call:

617-355-6000 +1-617-355-6000
Find a Doctor
Search by Clinician's Last Name or Specialty:
Select by Location:
Search by First Letter of Clinician's Last Name: *ABCDEFGHIJKLMNOPQRSTUVWXYZ
More optionsSearch
Condition & Treatments
Search for a Condition or Treatment:
View allSearch
The future of pediatrics will be forged by thinking differently, breaking paradigms and joining together in a shared vision of tackling the toughest challenges before us.”
- Sandra L. Fenwick, President and CEO