Fragile X Syndrome Medical Issues: Birth to Adolescence

Infants & Toddlers

Most infants with Fragile x syndrome (FXS) are healthy and don’t require extensive medical intervention. However there are some common medical conditions that can occur more often in babies with Fragile X syndrome.

Birth Defects

Babies with Fragile x syndrome have an increased chance of some congenital abnormalities such as cleft lip, cleft palate, clubfoot, congenital hip dislocation, and hernias. This may be related to loose connective tissue (more about this below).

Because these are all common birth defects among children without Fragile x syndrome, babies with these conditions are not routinely tested for Fragile x syndrome unless they present other symptoms, such as developmental delay, or a family history of Fragile x syndrome.

Low Muscle Tone

Many babies with Fragile x syndrome have hypotonia, which is low muscle tone. This is sometimes referred to as being “floppy,” which for a baby can cause difficulty in holding up their head, also known as “head lag.”

Because low muscle tone affects gross motor skills, such as sitting up or rolling over, hypotonia can contribute to the developmental delays often seen in babies and toddlers with Fragile x syndrome.

Digestive Disorders

Although many babies with Fragile x syndrome do well in the newborn period, others have difficulty with feeding, vomiting, or gastroesophageal reflux disease (known as GERD), a digestive disease in which stomach acid or bile irritates the lining of the esophagus (the tube connecting the mouth to the stomach.

This may be related to connective tissue abnormalities, low muscle tone (hypotonia), dysfunction of the gastroesophageal sphincter, or a hypersensitive gag reflex.

Some parents report that vomiting in babies with GERD can be resolved by positioning them upright after meals or feeding them thicker baby food. Occasionally, medication is needed to decrease reflux.

Babies will sometimes be diagnosed with what is called “failure to thrive.” This is typically related to difficulties in sucking, GERD, or an aversion to food textures. If feeding difficulties are a problem, particularly sucking or intolerance of certain food textures, consultation with an occupational or speech and language therapist, or therapies such as oral desensitization, oral stimulation, and oral motor coordination, can be helpful.

Ear & Sinus Infections

Beginning in the first year of life, frequent otitis media (middle ear infections) are a problem for many boys (and some girls) with Fragile X syndrome. In fact, the speech and language delays seen in children with Fragile X syndrome are often mistakenly attributed to chronic ear infections, sometimes delaying the Fragile X syndrome diagnosis.

Ear infections require treatment to avoid a hearing loss that could further compromise language development. If a conductive hearing loss persists after acute antibiotic treatment, ear tubes (most commonly referred to as PE — pressure equalizing — tubes, but also known as tympanostomy or ventilating tubes) are often recommended.

Recurrent sinusitis is also a common problem in Fragile X syndrome, which may be related to the facial structure or the connective tissue problems that lead to recurrent ear infections.

Children and Adolescents

Urinary Tract Infections

Some children (more often boys), with Fragile X syndrome, may have an increased susceptibility to urinary tract infections and reflux (the backing up of urine into the urethra and bladder). The pediatrician may suspect an infection if the child has a fever of unknown origin with no other explanation, and thus a urine sample will be obtained.


Approximately 20% of males and a smaller percentage of females with Fragile X syndrome have epilepsy. If your physician suspects your child is having seizures, often an EEG (electroencephalogram, which detects electrical activity in the brain) is performed. If seizures are confirmed, seizure medication is usually prescribed.

Eye Disorders

Children with Fragile X syndrome have an increased susceptibility for vision and eye disorders, which are common in childhood.

These include:

  • Strabismus: Also called “lazy eye,” this condition causes the eye to appear “crossed” or drifting to the middle. This is often due to low muscle tone in the eye, a symptom of the hypotonia present in many babies or children with Fragile X syndrome.
  • Ptosis: Drooping of the eyelid, again often related to low muscle tone.
  • Nystagmus: Shaking of the iris in a back and forth motion.
  • Myopia/Hyperopia: Subtle near- or farsightedness.

It is recommended that all children with Fragile X syndrome be referred to an ophthalmologist if the pediatrician suspects any of these common eye or vision conditions.

Connective Tissue Issues

Connective tissue is the tissue that holds together the body such as skin, muscles, tendons, cartilage, ligaments, bones, and blood vessels. Many individuals with Fragile X syndrome have differences in their connective tissue. Some of these connective tissue problems include:

  • Scoliosis: Curvature of the spine, usually not severe.
  • Flat feet: Also called pes planus.
  • Hernias: Inguinal (groin) hernias.
  • Cardiac murmur: Often a functional or innocent murmur, it is sometimes indicative of mitral valve prolapse (or MVP, which is improper closure of the valve between the heart’s upper and lower left chambers.). Occasionally an evaluation by a cardiologist is warranted to confirm MVP, and if confirmed, the cardiologist may recommend antibiotics prior to dental procedures or surgery.
  • Hyperflexible joints: Particularly of the wrists, fingers, and elbows.
  • Soft skin
  • Macroorchidism: Testicular volume normally increases during the early stages of puberty, but in boys with Fragile X syndrome this increase is usually quite dramatic, leading to macroorchidism (enlarged testicles). These changes are typical for Fragile X syndrome, and do not require intervention. Some boys with Fragile X syndrome develop large testicles prior to the onset of puberty.

Physical Problems in Fragile X Syndrome
Written for medical practitioners, our consensus document on physical problems in Fragile X syndrome provides additional information.

Seizures in Fragile X Syndrome
Recommendations for medical practitioners on seizures related to Fragile X syndrome.