Thursday, February, 09, 2012

Fragile X syndrome

Table of Contents

Alternative Names

Martin-Bell syndrome; Marker X syndrome


Symptoms
  • Delay in crawling, walking, or twisting
  • Hand clapping or hand biting
  • Hyperactive or impulsive behavior
  • Mental retardation
  • Speech and language delay
  • Tendency to avoid eye contact

Physical signs may include:

  • Flat feet
  • Flexible joins and low muscle tone
  • Large body size
  • Large forehead or ears with a prominent jaw
  • Long face
  • Soft skin

Some of these problems are present at birth, while others may not develop until after puberty.

Family members who have fewer repeats in the FMR1 gene may not have mental retardation, but may have other problems. Women with less severe changes may have premature menopause or difficulty becoming pregnant. Both men and women may have problems with tremors and poor coordination.


Signs and tests

The person will have a family history of Fragile X syndrome (especially a male relative).

There are very few outward signs of Fragile X syndrome in babies. Some signs may include:

  • Large head circumference in babies
  • Mental retardation
  • Oversized testes (macro-orchidism) in males who have reached puberty
  • Subtle differences in facial characteristics

In females, excess shyness may be the only sign of the problem.

A genetic test called polymerase chain reaction (PCR) is used to diagnose this disease. This test looks for a mutation (called a triplet repeat) in the FMR1 gene.

In the past, a specific type of chromosome analysis was done. Such testing may still be available.


Review Date: 05/12/2010
Reviewed By: A.D.A.M. Editorial: David Zieve, MD, MPH, David Eltz. Previously reviewed by Diana Chambers, MS, EdD, Certified Genetics Counselor (ABMG), Charter Member of the ABGC, University of Tennessee, Memphis. Review provided by VeriMed HealthcareNetwork (8/11/2009).

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)