What is the Difference Between Down Syndrome and Turner Syndrome

The key difference between Down syndrome and Turner syndrome is that Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, while Turner syndrome is a genetic disorder caused by the partial or complete missing of the X chromosome in females.

Aneuploidy is defined as the presence of an abnormal number of chromosomes in a biological cell. Hence, in aneuploidy conditions, a human cell may have 45 or 47 chromosomes instead of 46. Aneuploidy is usually caused by nondisjunction (chromosomes do not separate properly between two cells). It is of two main types as autosomal (Down syndrome) and sex chromosome (Turner and Klinefelter syndrome). Down syndrome and Turner syndrome are two different types of aneuploidy conditions.

CONTENTS

1. Overview and Key Difference
2. What is Down Syndrome
3. What is Turner Syndrome
4. Similarities – Down Syndrome and Turner Syndrome
5. Down Syndrome vs Turner Syndrome in Tabular Form
6. Summary – Down Syndrome vs Turner Syndrome

What is Down Syndrome?

Down syndrome is a genetic disorder that occurs due to the presence of all or part of a third of chromosome 21 in human cells. This syndrome is also known as trisomy 21. This genetic disorder is characterized by slow physical growth, mild to moderate intellectual disability, and characteristic facial features (flattened face, small head, short neck, protruding tongue, palpebral fissures, small ears, poor muscle tone, broad, short hands with a single crease in the palm, etc.). Normally, a person with Down syndrome has an IQ of 50, which is equal to an 8-year-old child. This disease was named after the British doctor John Langdon Down, who first described it in 1866. It is one of the most common chromosome abnormalities in humans.

The parents of affected individuals are normal in Down syndrome. Moreover, Down syndrome can be diagnosed through prenatal screening, direct observation, and genetic testing. There is no cure for this genetic disorder. Education and proper supportive care have been shown to improve the quality of people who are suffering from Down syndrome. The life expectancy is 50 to 60 in individuals with Down syndrome in developed countries with proper health care.

What is Turner syndrome?

Turner syndrome is a genetic disorder caused by the partial or complete missing of the X chromosome in females. It is also known as 45 X0 or 45X. The signs and symptoms of this disease include a short, webbed neck, low-set ears, low hairline at the back, short stature, swollen hands and feet at birth, no menstrual periods, underdeveloped breasts, inability to have children, heart defects, diabetes, low thyroid hormone, vision and hearing problems. Individuals with Turner syndrome have normal intelligence. Turner syndrome is also caused due to nondisjunction events.

Moreover, Turner syndrome is diagnosed through physical signs examination and genetic testing. Furthermore, there is no cure for Turner syndrome. However, human growth hormone injections may help increase adult height, estrogen replacement therapy may help breast and hip development, and reproductive technology may help with having children.

What are the Similarities Between Down Syndrome and Turner Syndrome?

• Down syndrome and Turner syndrome are two different types of aneuploidy conditions.
• Both conditions are rare genetic disorders.
• They are not inherited as they are caused due to non-disjunction, a sporadic event.
• Both conditions can be diagnosed through physical signs and genetic testing.
• There is no cure for both diseases.

What is the Difference Between Down Syndrome and Turner Syndrome?

Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, while Turner syndrome is a genetic disorder caused by the partial or complete missing of the X chromosome in females. Thus, this is the key difference between Down syndrome and Turner syndrome. Furthermore, Down syndrome is an autosomal aneuploidy, while Turner syndrome is a sex chromosome aneuploidy.

The below infographic presents the differences between Down syndrome and Turner syndrome in tabular form for side-by-side comparison.

Summary – Down Syndrome vs Turner Syndrome

Aneuploidy is the presence of an abnormal chromosome number in a biological cell. It means, in these conditions, the human cell may have 45 or 47 chromosomes instead of 46 chromosomes. Down syndrome and Turner syndrome are two different types of aneuploidy conditions. Down syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 21, while Turner syndrome is a genetic disorder caused by the partial or complete missing of the X chromosome in females. So, this summarises the difference between Down syndrome and Turner syndrome.

Reference:

1. “Down Syndrome.” Mayo Clinic, Mayo Foundation for Medical Education and Research.
2. “Turner Syndrome: Causes, Symptoms, Diagnosis & Treatment.” Cleveland Clinic.

Image Courtesy:

1. “Child With Down Syndrome” (CC0) via Public Domain Pictures.
2. “Karyotype of proband with Neurofibromatosis type 1, Tuberous Sclerosis complex and Turner Syndrome. The arrow indicates the presence of only one X chromosome in Karyotype” By Malini S. Suttur, Savitha R. Mysore, Balasundaram Krishnamurthy, and Ramachandra B. Nallur – NCBI – (CC BY 2.0) via Commons Wikimedia