Stickler Syndrome, a Disorder due to Damage to Collagen-Forming Genes
What happens
when collagen breaks down?
Stickler syndrome
is a disorder caused by the breakdown of genes that produce collagen. Collagen
is one of the most abundant and abundant connective tissue proteins in the
body, which gives tissue shape and strength.
The occurrence of
such damage can cause abnormalities in various limbs. Stickler syndrome often
affects collagen
used to produce joint cartilage and jelly-like materials (vitreous) in the
eyes. What are the signs and symptoms to watch out for? Here's the full review.
1. Signs and symptoms of Stickler syndrome
Stickler syndrome
is divided into five subtypes based on its causes and symptoms, namely types I,
II, III, IV, and V. Symptoms vary significantly from person to person, even in
the same family and the severity.
In general, the clinical picture of Stickler syndrome includes:
- • Characteristic of a flat face due
to abnormal development of the bones in the center of the face. Commonly
described as Pierre-Robin sequences, such as a high arched cleft palate, a
tongue that is further back than usual, a short chin, and a small lower
jaw. The combination of these features can cause eating problems and
difficulty breathing.
- Eye problems, including
nearsightedness, vitreoretinal degeneration, glaucoma, cataracts, holes,
or retinal detachment. In some cases, eye problems can cause blindness.
- Middle ear abnormalities include
hearing loss, sensorineural, recurrent ear infections, fluid in the ear,
or hypermobility of the ear bones.
- Skeletal abnormalities include a curved
spine (scoliosis or kyphosis), hypermobile joints, early-onset arthritis, chest deformities, childhood
hip disorders (Legg-Calve-Perthes disease), and common joint injuries
problems.
- Dental abnormalities, including
malocclusion.
- Hypertonia, flat feet, and long
fingers.
Eye abnormalities
and hearing loss have different severity of each type. Stickler syndrome type I
has the highest risk of retinal discharge, types II and III tend to have
hearing loss, but type III is often called non-ocular Stickler syndrome.
Meanwhile, cases of type IV and V are still rare.
2. Causes of Stickler syndrome
The disorder,
which is estimated to affect about 1 in 7,500 to 9,000 births, is caused by a mutation
in collagen-forming genes. Each type has a different cause of gene mutation,
namely:
- Type I is caused by a mutation of the
COL2A1 gene. About 80 to 90 percent of cases are classified as type I.
- Type II is caused by a col11A1 gene
mutation in about 10 to 20 percent of cases.
- Type III is caused by a mutation of
the COL11A2 gene.
- Type IV is caused by a mutation of
the COL9A1 gene. It has been identified in three families in Turkey and
Morocco.
- Type V is caused by a col9A2 gene
mutation that has been reported in families in India.
All of these
genes associated with Stickler syndrome provide clues to making collagen
components. The presence of such mutations causes collagen production and
formation to be disrupted, which can interfere with the development of
connective tissue in various bodies and lead to stickler syndrome features.
As reported by
MedlinePlus, not all individuals with Stickler syndrome have mutations in one
of the known genes. Researchers believe that mutations in other genes can cause
this condition, but these genes have not been identified.
3. This gene mutation can be passed down from the family or occur spontaneously in someone affected by it.
Most cases of
Stickler syndrome are inherited from a predominantly autosomal family, i.e.,
one copy of a defective gene is enough to cause the disorder. In some cases,
the condition can also occur due to a new mutation(de novo), which is
not family-related and occurs randomly in the affected individual for no known
reason.
In autosomal
dominant inheritance patterns, abnormal genes can be inherited from one parent,
a 50 percent risk of transmission in each pregnancy. This pattern of
inheritance occurs in Stickler syndrome types I, II, and III.
In rarer cases,
mutations are caused by autosomal recessive inheritance patterns, which is when
damaged genes are obtained from both parents. This pattern of inheritance
occurs in Stickler syndrome types IV and V.
4. Stickler syndrome diagnosis
The disorder,
first described by Gunnar Stickler in 1965, was diagnosed based on a thorough
clinical evaluation, a detailed patient's medical history, and the identification
of typical symptom findings.
To date, there
are no standard diagnostic criteria for this syndrome. Some tests such as
X-rays, eye tests, hearing tests, and/or genetic testing may help establish a
diagnosis.
5. Treatment is directed at specific symptoms that are visible
There is no cure
for this rare disorder. However, some treatments can help manage symptoms, such
as therapy or surgery.
According to the
Mayo Clinic, the following treatments are needed:
• Therapy, which
includes speech therapy, physical therapy, hearing aids, and special education
• Surgery may
include a tracheostomy (to correct a tiny jaw and a displaced tongue), jaw
surgery, cleft palate repair, ear tubes, eye surgery, joint replacement, or
spinal brace or fusion surgery
Those are some
medical facts of Stickler syndrome. Early recognition of this syndrome is significant
to get the proper treatment. Genetic counseling will also be of benefit to the
affected family.
