Megalocornea Mental Retardation Syndrome

National Organization for Rare Disorders, Inc.

It is possible that the main title of the report Megalocornea Mental Retardation Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.


  • MMR Syndrome
  • Neuhauser Syndrome

Disorder Subdivisions

  • None

General Discussion

Megalocornea-Mental Retardation Syndrome is an extremely rare genetic disorder characterized by distinctive abnormalities of the eyes, diminished muscle tone that is apparent at birth (congenital hypotonia), and varying degrees of mental retardation. In some cases, additional abnormalities may also be present. The range and severity of symptoms and physical findings may vary from case to case.

In most infants with Megalocornea-Mental Retardation Syndrome, the front, clear portion of the eyes through which light passes may be abnormally large (megalocornea). Both eyes are usually affected (bilateral involvement). Many affected infants also have additional eye (ocular) abnormalities including underdevelopment of the colored portion of the eyes (iris hypoplasia), abnormal "unsteadiness" of the irises during eye movements (iridodonesis), and/or other ocular abnormalities, potentially leading to varying degrees of visual impairment. In addition to abnormally diminished muscle tone (hypotonia), most affected infants also have additional neuromuscular abnormalities including abnormal delays in the acquisition of skills requiring the coordination of mental and muscular activities (psychomotor retardation) and/or an impaired ability to coordinate voluntary movements (ataxia). In most cases, affected infants and children also have moderate to severe mental retardation.

In some cases, infants and children with Megalocornea-Mental Retardation Syndrome may have additional abnormalities including short stature; episodes of uncontrolled electrical disturbances in the brain (seizures); and/or certain distinctive abnormalities of the head and facial (craniofacial) area. Such craniofacial malformations may include an unusually prominent forehead (frontal bossing), widely spaced eyes (ocular hypertelorism), a long upper lip, an abnormally small lower jaw (hypoplastic mandible), and/or unusually large and/or "cup-shaped" ears. In most cases, Megalocornea-Mental Retardation Syndrome appears to occur randomly for unknown reasons (sporadically). In other cases, the disorder is thought to be inherited as an autosomal recessive genetic trait.


Human Growth Foundation
997 Glen Cove Avenue
Glen Head, NY 11545
Tel: (516)671-4041
Fax: (516)671-4055
Tel: (800)451-6434

Children's Craniofacial Association
13140 Coit Road
Suite 517
Dallas, TX 75240
Tel: (214)570-9099
Fax: (214)570-8811
Tel: (800)535-3643

National Association for Visually Handicapped
22 West 21st Street
New York, NY 10010
Tel: (212)889-3141
Fax: (212)727-2931

National Association for Parents of Children with Visual Impairments (NAPVI)
P.O. Box 317
Watertown, MA 02472
Tel: (617)972-7441
Fax: (617)972-7444
Tel: (800)562-6265

American Council of the Blind
2200 Wilson Boulevard, Suite 650
Arlington, VA 22201
Tel: (202)467-5081
Fax: (202)465-5085
Tel: (800)424-8666

Glaucoma Research Foundation
251 Post Street, Suite 600
San Francisco, CA 94108
Tel: (415)986-3162
Fax: (415)986-3763
Tel: (800)826-6693

NIH/National Eye Institute
Building 31 Rm 6A32
31 Center Dr MSC 2510
Bethesda, MD 20892-2510
United States
Tel: (301)496-5248
Fax: (301)402-1065

National Institute of Neurological Disorders and Stroke (NINDS)
P.O. Box 5801
Bethesda, MD 20824
Tel: (301)496-5751
Fax: (301)402-2186
Tel: (800)352-9424
TDD: (301)468-5981

Craniofacial Foundation of America
975 East Third Street
Chattanooga, TN 37403
Tel: (423)778-9176
Fax: (423)778-8172
Tel: (800)418-3223

Genetic and Rare Diseases (GARD) Information Center
PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311
TDD: (888)205-3223

For a Complete Report

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see

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