Trisomy 9- Causes, Symptoms, and Treatment

Introduction:

Trisomy 9 is a disease rarely seen and is often a deadly chromosomal disease. This condition is observed in around 2.4 percent of pregnancies resulting in loss early in the 20th week, commonly called spontaneous abortion (miscarriage).

What Is Trisomy 9?

Trisomy 9 is a kind of chromosomal deformity of the 9th chromosome. Similar to trisomy 21 (also called Down syndrome), trisomy 9 is seen when there are three copies (in place of the usual two copies) of chromosome 9 in the cells of the fetus. Trisomy 9 occurs is seen less frequently as compared to trisomy 21 and has severe consequences. The survival rate in the case of trisomy 9 is too less. Many cases of trisomy 9 are not acquired. They are seen to occur sporadically as a random process during the formation and maturation of reproductive cells (the egg and the sperm) or when the process of fertilization of the egg takes place.

What Are the Types of Trisomy 9?

There are three types of trisomy 9. Each class has unique genetic characteristics and physical features. These can be described as:

• Full Trisomy 9: In full trisomy 9, all of the cells in the body of the baby and placenta have three copies of chromosome 9. Unfortunately, this condition is frequently associated with fatality, leading to the death of many fetuses in the initial trimester itself.

• Partial Trisomy 9: In partial trisomy 9, there exists, two copies of the ninth chromosome and an additional partial copy. Partial trisomy 9 does not always affect the life expectancy of the infant. However, babies with such diseases have many health and developmental issues.

• Mosaic Trisomy 9: Mosaic trisomy is present in a few cells of the body, while other cells have a normal set of chromosomes. Many cases of all trisomies are mosaic trisomy 9. Many patients die in infancy due to health issues that occur due to the disorder.

What Are the Signs and Symptoms of Trisomy 9?

The signs and symptoms seen in trisomy 9 differ too much. Some can be detected before the birth of the child, while others might not appear even after birth. During prenatal stages, ultrasound examinations often reveal usual symptoms such as abnormal fetal heart rate and brain and spinal cord deformities.

The facial features of the child having this condition have a miniature head, a wide nose with a rounded tip, the presence of a cleft lip and or cleft palate, a small jaw, ears set lower than usual, and small eyes and eyelids moving upwards. Vision problems also persist. Some of the other problems seen in such children are:

• Dislocation of the joints.

• Underdeveloped genital organs.

• Undescended testes are seen in male infants.

• Kidney cysts are seen.

• Feeding and breathing issues at birth.

• Failure to thrive.

• Short stature.

• Variable cognitive disabilities and developmental delays.

What Causes Trisomy 9?

Mainly trisomy 9 cases are a result of random errors in the process of chromosomal separation, called nondisjunction. This error leads to abnormal numbers of chromosomes in some eggs or sperm. If an egg or sperm cell carries an additional chromosome 9 and is involved in embryo formation, it results in an extra copy of chromosome 9 in all cells. While in some cases, the egg and sperm might have a normal number of chromosomes, an error might occur during cellular division after fertilization.

What Factors Increase the Risk of Trisomy 9?

Mainly trisomy 9 occurs randomly rather than as a result of specific, known risk factors. An exception occurs when one or both parents have a condition called a balanced translocation, which impacts chromosome 9. In such cases, a correlation has been discovered between this condition and a heightened likelihood of giving birth to a baby with partial trisomy 9.

How Is Trisomy 9 Diagnosed?

• Chorionic Villus Sampling(CVS): Trisomy 9 is usually diagnosed after a miscarriage, but it can also be identified during pregnancy by chorionic villus sampling (CVS) or amniocentesis. A doctor can advise for a test of the baby's chromosome (karyotype) by using placental tissue from CVS or fetal cells from amniocentesis. If signs of trisomy 9 are observed after birth, a diagnostic confirmation can be obtained by completing a karyotype.

• Prenatal ultrasound: Usual findings during a prenatal ultrasound are fetal heart defects and brain and spinal cord malformations.

How Is Trisomy 9 Treated?

• There is no definite treatment for trisomy 9. However, its symptoms can be controlled with the combined efforts of pediatrics, cardiologists, surgeons, and physicians who identify and treat the problem of the skeleton, joints, muscles, and tissues.

• Treatment with specific medications, surgical intervention, or other means might be required in affected individuals with congenital heart defects. In infants with hydrocephalus, disease management might include giving particular medications to reduce the rate of cerebrospinal fluid (CSF) formation, shunting, or other measures. (shunts are the devices that can drain excess CSF from the brain to another part of the body for absorption into the bloodstream). In some instances, medical professionals might recommend surgery to treat and rectify craniofacial, musculoskeletal, genital, or other issues associated with the disorder. The specific surgical procedures undertaken will depend on the type and severity of the anatomical variations, the presence of related symptoms, and additional relevant factors.

• Early intervention services may also be important to ensure that affected children reach their potential. Special services that might be helpful are special remedial education, physical therapy, occupational therapy, speech therapy, feeding therapy, and other medical, social, and vocational services.

• Genetic counseling is advised for families of affected children. Another treatment for this disease is symptomatic and supportive.

Conclusion:

Trisomy 9 is an uncommon chromosomal disorder characterized by an additional copy of chromosome 9 (trisomy) within the cells of the developing fetus. It can be seen due to random error during chromosomal separation. It can be categorized into three types: full trisomy 9, partial trisomy 9, and mosaic trisomy 9. Some symptoms of trisomy 9 include heart defects, joint problems such as dislocation, descendants of testes in male infants, etc. It can be diagnosed with the help of prenatal ultrasound or CVS. It has no definitive treatment, but its symptoms can be regulated, such as heart defects, vision defects, hydrocephalus, etc.