What Is Chediak-Higashi
Albinism is a lack of color in
the skin, hair, and eyes. Chediak-Higashi syndrome (CHS) is an extremely rare
form of partial albinism that’s accompanied by problems with the immune and
This specific type of albinism also
causes vision problems such as sensitivity to light, reduced sharpness, and
involuntary eye movement.
Types of CHS
There are two types of CHS: classic
The classic form is present
at birth or occurs soon after birth.
The late-onset form occurs
later in childhood or adulthood. It’s much milder than the classic form. People
with late-onset CHS experience minimal pigmentation changes and are less likely
to develop severe, recurrent infections. Adults with late-onset forms of the
disorder, however, have a significant risk of developing neurological problems
such as difficulty with balance and movement, tremors, weakness in the arms and
legs, and slow mental development.
What Causes CHS?
CHS is an inherited condition caused
by a defect in the LYST gene (also called the CHS1 gene). The LYST gene gives
the body instructions on how to make the protein that’s responsible for
transporting certain materials to your lysosomes.
Lysosomes are structures
inside some of your cells that break down toxins, destroy bacteria, and recycle
worn out cell components. The defect in the LYST gene causes the lysosomes to
grow too large. The enlarged lysosomes interfere with normal cell functions.
They prevent cells from seeking out and killing bacteria, so your body isn’t
able to protect itself from recurring infections.
In pigment cells, abnormally large
structures called melanosomes (related to lysosomes) produce and
distribute melanin. Melanin is the pigment that gives color to skin, hair, and
eyes. People with CHS have albinism because melanin is trapped within the
larger cell structures.
Chediak-Higashi is an autosomal
recessive inherited disorder. Both parents of a child with this type of genetic
disorder carry a copy of the defective gene, but they usually don’t show signs
of the condition.
If only one parent passes on the
defective gene, the child won't have the syndrome but may be a carrier. That
means they could pass the gene on to their children.
What Are the Symptoms of
Symptoms of classic CHS include:
- brown or
light-colored hair with a silvery sheen
- light colored
- white or
grayish skin tone
(involuntary eye movements)
infections in the lungs, skin, and mucous membranes
Other symptoms that infants or young
children with CHS may experience are:
- poor vision
(eyes are sensitive to bright light)
- slowed mental
- blood clotting
problems resulting in abnormal bruising and bleeding
According to a study, roughly 85
percent of children with CHS reach a severe stage called the accelerated phase.
Scientists think the accelerated phase is triggered by a viral infection.
During this phase, abnormal white
blood cells divide rapidly and uncontrollably, which can cause:
- serious infections
- organ failure
Older children and adults with
late-onset CHS have milder symptoms, less noticeable pigmentation issues, and
fewer infections. They may still develop seizures and nervous system problems
that can cause:
How Is CHS Diagnosed?
To diagnose CHS, your doctor will
first look at your medical history for other indicators of the disease, such as
frequent infections. A physical exam and certain tests are then performed to
make a diagnosis. A physical exam can show signs of a swollen liver or spleen,
or jaundice (yellowing of skin and eyes). Tests may include:
- complete blood
count to identify abnormal white blood cells
testing to identify the defective LYST gene
exam (eye exam) to determine reduced eye pigmentation or presence
of involuntary eye movement
How Is CHS Treated?
There is no cure for CHS. Treatment
consists of managing symptoms.
Antibiotics will treat
infections. Corrective eye lenses may be prescribed to improve
vision. Bone marrow transplants may help treat defects in the immune
system. This procedure is most effective when performed before a person
develops the accelerated phase of the disorder.
If your child is in the accelerated
phase, your doctor may prescribe antiviral medications and chemotherapy drugs
to try to minimize the spread of the defective cells.
Long-Term Outlook for CHS
Most children with the classic form of
CHS die within the first 10 years of their lives as a result of chronic
infections or organ failure. Some children do live longer than 10 years.
People with late-onset CHS may live
with the disorder into early adulthood but typically have shorter lifespans due
Contact your doctor about genetic
counseling if you have CHS or if you have a family history of the syndrome and
are planning to have children. Genetic testing may be available to see whether
you are carrying the defective LYST gene and the likelihood that your child
will inherit the syndrome. There are multiple possible mutations in the LYST
gene that cause CHS. The specific gene mutation in your family must be
identified before any genetic or prenatal testing is available.
Prenatal testing may also be an option
for at-risk pregnancies. This type of testing involves analyzing a small sample
of DNA extracted from the amniotic fluid (the clear fluid that surrounds and
protects a baby in the womb) to test for mutated genes.