Chromosome 12q Deletion Syndrome: Clinical Characteristics, Diagnosis, and Management Approaches

Introduction:

Chromosome 12q deletion is a chromosome defect that arises when a copy of the genetic material on the long arm (q) of chromosome 12 is absent. The size, location, and genes involved all affect the disease's severity and the signs and symptoms. These can be severe or mild, based on the amount of genetic material lost, the number of genes impacted, and the function of the affected genes. The disease affects newborn children (congenital manifestation). It may lead to atypical facial features, growth and developmental abnormalities, and hearing or visual impairment. In addition, chromosome 12q Deletion Syndrome can have side effects like malnutrition from difficulty feeding, missing developmental milestones, and a lower quality of life. Most cases are not inherited; however, individuals can pass the deletion on to their offspring. Therefore, each person's signs and symptoms will determine how they will be treated.

What Are the Other Names for Chromosome 12q Deletion?

• 12q Deletion Syndrome.

• Monosomy 12q Syndrome.

• Partial Monosomy 12q.

• Deletion 12q.

• Monosomy 12q.

• 12q deletion.

• 12q monosomy.

Who Gets Chromosome 12q Deletion Syndrome?

• Chromosome 12q deletion Syndrome is an extremely rare congenital condition. The onset of symptoms could happen before, during, or after childbirth.

• Individuals with moderate signs and symptoms may be untreated for a long time. As a result, determining the true incidence of the disorder may be difficult.

• Males and females may be affected.

• People of all races and ethnicities may be affected globally.

What Are the Risk Factors (Predisposing Factors) for Chromosome 12q Deletion Syndrome?

Most people have no known risk factors for Chromosome 12q Deletion Syndrome.

• A family history may be a significant risk factor for 12q Deletion Syndrome in some people.

• There are no known environmental or lifestyle (including nutritional) risk factors.

• The expectant mother's actions or inactions before, during, or after pregnancy do not lead to the syndrome.

Understanding that having a risk factor does not ensure that one will get the disease. A risk factor increases a person's likelihood of developing a condition compared to someone without a risk factor. Different risk factors have different levels of significance. Furthermore, the absence of a risk factor does not indicate that a person would not get the disease. Therefore, it is always vital to address the impact of risk factors with the healthcare professional.

What Causes Chromosome 12q Deletion Syndrome?

Chromosome 12q Deletion Syndrome may have the following causes:

• The most frequent cause of the condition is a de-novo loss of genetic material in the long arm (q) of chromosome 12.

• Rarely, the disease may also be inherited from a parent.

• There are two 12 chromosomes in total. Children with chromosome 12q deletions often have one (chromosome 12) that is normal and one that is abnormal. The abnormality is characterized by chromosomal material loss.

What Are the Signs and Symptoms of Chromosome 12q Deletion Syndrome?

The signs and symptoms of chromosome 12q deletion syndrome vary for every individual. The associated signs and symptoms are determined by what material is deleted, the amount of deletion (quantity), the location, and the involvement of another chromosome. The following are common signs and symptoms of 12q deletion syndrome:

• Feeding difficulties.

• Small feet and hands.

• Hypotonia (poor muscle tone).

• Loss of hearing.

• Vision problems.

• Difficulty walking and standing.

• Seizures.

• Learning and speech disabilities.

• Delays in development.

• Behavioral problems.

Distinctive facial characteristics, such as:

• Small-sized head.

• Widely-spaced eyes.

• Large and prominent forehead.

• Abnormal and low-set ears.

• Cleft lip.

• Flat nose.

What Are the Complications of Chromosome 12q Deletion Syndrome?

Complications can happen with or without therapy and occasionally even as a result. The complications of Chromosome 12q deletion include the following-

• Emotional stress for parents and caregivers.

• Pregnancy complications.

• Delayed achievement of a milestone.

• Severe intellectual disability.

• Aggressive or violent behavior.

• Physical abnormalities.

• Decreased quality of life.

How Is Chromosome 12q Deletion Syndrome Diagnosed?

Children may have a variety of symptoms. Some kids with mild signs and symptoms may go untreated throughout their lives. Therefore, the healthcare professional should have a high index of suspicion to include chromosome 12q deletion syndrome in the differential diagnosis due to the rarity of the disorder. Often, specific testing is required to confirm the disease. The following tests are used to diagnose 12q Deletion Syndrome:

• Complete physical examination and review of medical history, including family medical history.

• Assessment of the signs and symptoms, including testing of the immune system, central nervous system, genitalia, muscles, vision, hearing, and other body functions.

• Assessment of hearing and vision using various tests.

• Laboratory tests, including sex hormone studies, thyroid function testing, serum calcium testing, renal function testing, urine testing, and tests for electrolyte levels, etc.

• Radiological examinations of the affected areas.

• The neurological examination includes central nervous system testing.

• Behavioral study.

• Abdomen ultrasound is a part of prenatal studies.

Specialized genetic testing techniques are necessary to confirm the diagnosis. It might comprise:

• Fluorescence in situ hybridization (FISH) testing.

• Array comparative genomic hybridization (array-CGH).

• DNA sequencing.

How to Treat Chromosome 12Q Deletion Syndrome?

There is no treatment for chromosome 12q deletion syndrome. The main goal of treatment is to control the symptoms, and complications that may develop. People with minor symptoms may only need monitoring and minimal medical intervention. A multidisciplinary team of experts manages the condition made up of pediatricians, ophthalmologists, otolaryngologists, neurologists, internists, cardiologists, endocrinologists, surgeons, and other medical personnel. The following are possible 12q deletion syndrome treatments-

• Using cochlear implants and hearing aids.

• Using touch-screen computers, visual and tactile literature, music therapy, and other learning methods.

• The use of sign language may be advantageous in speech and language therapy.

• Physiotherapy for weak muscles involves a daily workout routine.

• Motor skill development through regular exercises, swimming, and other adapted activities.

• Feeding tubes (temporary), medicines, thickeners, special meals, and nutritional supplements help with feeding issues.

• Surgical correction of physical flaws as determined by a healthcare specialist, such as cleft lip and surgical repair.

• Use of appropriate glasses and surgical vision correction.

• Surgical repair (orchiopexy) of undescended testicles and other genital abnormalities.

• Behavioral change, psychotherapy, and the use of appropriate discipline methods.

• Occupational therapy.

• Physical checkups and periodic medical screenings with testing are strongly advised.

What Is the Prognosis (Outlook) of Chromosome 12q Deletion Syndrome?

The severity of the signs, symptoms, and related complications determines the prognosis of chromosome 12q deletion syndrome.

• The outlook is better for people with mild problems than those with severe symptoms and complications.

• The size, location, and genes involved all have a significant role in determining the severity of the disease and the associated signs and symptoms.

• Some kids might need medical care and support for the rest of their lives.

Conclusion:

Chromosome 12q deletion Syndrome could not be prevented because many of these genetic abnormalities are found at or after childbirth. There is typically no family history of the condition because most cases are sporadic. Rarely could this disorder run in families. Prenatal diagnosis and genetic testing of the expectant parents may aid in a better knowledge of pregnancy risks. Genetic counseling will help determine risks before making child-bearing decisions if there is a family history of the condition. Hence, ongoing research focuses on the possibility of treating and preventing inherited and acquired genetic disorders.