Symptoms:

• Hyperactive behavior
• Large body size
• Large forehead or ears with a prominent jaw
• Large testicles (macro-orchidism) after the beginning of puberty
• Mental retardation
• Tendency to avoid eye contact

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 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.