What is Wolf-Hirshhorn syndrome?

Finding out if your child has Wolf-Hirschhorn syndrome, also known as 4p syndrome, can be very difficult. Naturally, you have many questions about what causes it and how it is treated.

Wolf-Hirschhorn is a rare genetic disorder that occurs in your child when part of chromosome 4 is removed. It occurs when cells divide abnormally during reproduction.

When part of a chromosome is missing, it can lead to disruption of normal development. The deleted chromosome 4 causes Wolf-Hirschhorn traits, including facial features such as wide-set eyes, a distinct bulge on the forehead, a broad nose, and low-set ears.

Each case is individual, since the number of symptoms depends on the number of chromosomes removed.

What are the reasons?

Doctors are not sure what causes this spontaneous genetic change that occurs during a child's development. The "bad" chromosome is usually not inherited from either parent; the deletion usually occurs after fertilization. Doctors believe that three different genes could be removed from chromosome 4, all of which are important for early development.

Each missing gene causes a specific set of disease symptoms. For example, one of them is associated with facial abnormalities, while the other seems to cause seizures that affect almost all children with Wolff-Hirschhorn disease.

However, sometimes Wolff-Hirschhorn syndrome occurs when one of the parents has a so-called "balanced translocation". This means that at least two of their chromosomes have broken and switched places during their development. This usually causes no symptoms in that parent as the chromosomes are still balanced. But it increases a person's chances of having a child with a chromosome disorder, including Wolf-Hirschhorn.

You can take a genetic test to see if you have a balanced translocation.

What are the symptoms?

Wolf-Hirshhorn affects many parts of the body, both physical and mental. The most common symptoms are facial abnormalities, developmental delay, mental retardation, and seizures.

Other problems your child may have include:

Bulging, wide-set eyes
Droopy eyelids and other eye problems
Cleft lip or palate
Downturned mouth
Low birth weight
Microcephaly, or an unusually small head
Underdeveloped muscles
Scoliosis
Heart and kidney problems
Failure to thrive

How is it diagnosed?

Sometimes your doctor can detect physical signs of Wolff-Hirschhorn syndrome with routine ultrasounds during the first trimester of pregnancy. Or chromosomal problems can show up in what's called an expanded cell-free DNA test. But these are only screenings, not diagnostic tests. Your doctor will need to do more tests to find out if your child has Wolf-Hirschhorn.

A test that can detect more than 95% of Wolf-Hirschhorn's chromosomal deletions is called a "fluorescent in situ hybridization" test. Tests done after the baby is born can also detect a partial deletion of a chromosome.

If your doctor confirms that your child has a Wolf-Hirschhorn, they may suggest several imaging tests to fully understand all of the affected areas of your child's body. You and your partner should also be tested if you plan to have more children in the future.