Swiss Cheese Cartilage Syndrome - Causes, Symptoms, Diagnosis, and Treatment

Introduction:

Swiss Cheese Cartilage Syndrome (SCCS) is an extremely rare skeletal condition with a distinctive skeletal structure in radiological findings. This condition was initially reported in 1952 by Dr. Wilhelm Kneist in a three years old girl with various skeletal deformities and restricted joint mobility. This condition is known as the Kneist syndrome, Kneist Dysplasia, Kneist Chondrodystrophy, or Metatrophic dysplasia type II. This condition is a form of skeletal dysplasia and dwarfism. This article will discuss Swiss cheese cartilage syndrome, its symptoms, causes, diagnosis, and treatment options in detail.

What Is Swiss Cheese Cartilage Syndrome?

Swiss cheese cartilage syndrome is a rare genetic condition characterized by short stature, malformed bones, skeletal deformities, and other problems. This condition comes under skeletal dysplasia, in which abnormalities in the development of bones and cartilage. It is a genetic condition that occurs due to the genetic alteration of the COL2A1 gene, and it is inherited in an autosomal dominant pattern. This condition has distinctive clinical and radiological features. As of now, there is no cure for the disease. However, there are various symptomatic and supportive treatment options.

What Causes Swiss Cheese Cartilage Syndrome?

Swiss cheese cartilage syndrome is a genetic condition with abnormal alterations in the gene COL2A1 (collagen type 2 alpha 1 gene). The gene that is responsible for the formation of type II collagen. The type of collagen is usually present in bone cartilage (the flexible connective tissue that covers and protects the bones in the joints) and in the vitreous humor (a transparent, gel-like substance in the posterior chamber of the eye).

This collagen type is essential for forming bone and other connective tissue structures to form the body's skeletal system. Genetic alterations in the gene COL2A1 interfere with the assembly of collagen type 2 molecules, resulting in malformed bone and cartilage tissues and other skeletal deformities and defects in vision.

Swiss cheese cartilage syndrome is inherited in an autosomal dominant pattern. The condition that inherits in an autosomal manner means the presence of the mutated gene in the non-sex chromosomes (the first 22 pairs of chromosomes other than the X and Y chromosome). Dominant inheritance means that only a sole copy of the altered gene is sufficient to cause the genetic condition.

What Are the Symptoms of the Swiss Cheese Cartilage Syndrome?

Swiss cheese cartilage syndrome symptoms usually begin to appear during four weeks of age and in infancy.

• Short Stature: Affected patients typically have short stature with disproportionate legs and hands.

• Swiss Cheese Appearance: Brittle bone cartilage makes Swiss cheese appear with small holes in the cartilage.

• Bell-Shaped Thorax: Abnormal curvature of the backbone may result in a disproportionate trunk region. The chest gives a bell-shaped appearance with constricted superior portion and an expanded inferior portion of the ribcage.

• Dysmorphic Facial Features: An unusually flat face, protrusion of the eyes, and flattening of the top part of the nose.

• Eye Involvement: The patient may have short-sightedness, cataract (clouding in the lens of the eyes), and retinal detachment (a condition in which the sensitive tissue of the eye called the retina is pulled away from the supporting tissue). Other states like drooping eyelids, glaucoma (progressive damage to the optic nerve of the eye), and possible blindness may also be seen.

• Cleft Palate: An abnormal opening on the roof of the mouth.

• Inguinal Hernia: Soft tissue bulging in the weaker part of the lower abdominal muscles.

• Hearing Loss: Chronic hearing loss can occur.

• Joint Problems: Enlarged joints are common.

• Shorter Limbs: Limbs appears to be shorter.

• Stability Concerns: Lack of stability in the cervical part of the spine.

How Is Swiss Cheese Cartilage Syndrome Diagnosed?

Diagnosis of SCCS is usually made by performing a detailed history of the patient's condition and the family's medical history. The doctor will perform a thorough physical examination of the patient. The doctor may perform other diagnostic tests in the diagnosis of this condition.

Radiographic examinations such as an X-ray to visualize the bone structures. General radiographic findings of these patients include:

• Shorter limbs.
• Non-ossified epiphyseal bones (round end regions of the long bones).
• Presence of radiolucent vertebral defects (coronal clefts).
• Dumbbell-shaped femur bone (thigh bone).
• Abnormal lateral curvature of the backbone.
• Malformed parts of the long bones.

Other investigation techniques like MRI (Magnetic resonance Imaging) and CT (Computed Tomography) may also be performed. The doctor may perform genetic screening for the affected patient and the parents to assess the individual's DNA (Deoxyribonucleic Acid).

The clinician may perform an arthrogram, an imaging test involving the injection of a contrast medium into the hips, knee, and ankle to evaluate the cartilage in the joints. This condition may also be diagnosed during the prenatal examination of the fetus during pregnancy.

What Are the Treatment Options for Swiss Cheese Cartilage Syndrome?

Since Swiss cheese cartilage syndrome has a multisystemic involvement, the affected patients are kept under careful monitoring, and treatments are given based on the symptoms and complications of the patients.

• The affected child is referred to a pediatric surgeon for routine care and the treatment of skeletal abnormalities, cleft palate, and craniofacial anomalies.

• The doctor may plan an individualized treatment program based on the condition of the patient and the severity of the symptoms.

• Patients are referred to an orthopedic surgeon to treat bone and joint problems. The patient may require surgical interventions such as extension osteotomy to manage limited joint motion, spinal fusion surgery in patients with abnormal spine curvature, and retinal detachment repair.

• Other non-surgical treatment options may include bracing and physical therapy.

• The patient may require oxygen support and mechanical ventilation in severe cases with breathing difficulties.

• Affected patients with other eye defects are referred to an ophthalmologist.

• The patient and their family are referred for genetic counseling.

Conclusion:

Swiss cheese cartilage syndrome is an uncommon genetic condition characterized by short stature, skeletal deformities, and other malformed bones and cartilage. This condition damages multiple systems affecting vision, hearing, breathing difficulties, etc. They are caused due to the abnormal alteration of the gene COL2A1, and they are inherited in an autosomal dominant pattern. The condition's prognosis depends on the severity of the patient's symptoms. Individuals with a familial history of the condition are advised to genetic counseling before planning for a pregnancy.