10 Questions
What is the result of a deletion of a section of the X chromosome during meiosis?
A mosaic karyotype with a partial X chromosome
What is the effect of having only one complete X chromosome on the female reproductive system?
An increase in the rate of egg loss
What is the consequence of having streak ovaries in Turner syndrome?
Underproduction of sex hormones
Why does the body produce more follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in Turner syndrome?
To stimulate estrogen secretion by the ovaries
What is the consequence of having a single copy of the SHOX gene in Turner syndrome?
Short stature
What is the percentage of cells with the 45, X karyotype that determines the presence of abnormalities linked with Turner syndrome?
It varies from person to person
What is the most common cause of primary amenorrhea in females?
Turner syndrome
What is the name of the congenital abnormality where the two kidneys become fused during fetal development?
Horseshoe kidney
What is the term for the bluish or purplish discoloration of the lower limbs due to coarctation of the aorta?
Cyanosis
What is the purpose of growth hormone therapy in childhood for individuals with Turner syndrome?
To promote bone growth and height
Study Notes
Turner Syndrome Karyotype
- The least common karyotype in Turner syndrome involves a partial deletion of the X chromosome, resulting in a mosaic karyotype.
- This can occur during meiosis or mitosis, and the errors are thought to happen randomly.
Effects on Female Reproductive System
- Having only one complete X chromosome increases the rate of egg loss, leading to a complete loss of eggs by two years of age.
- This results in "menopause before menarche" and causes the ovaries to fail to develop normally, becoming non-functional, fibrous, and "streak" ovaries.
- The ovaries are unable to produce sex hormones, leading to hypogonadism and low estrogen levels.
- The body responds by producing more follicle-stimulating hormone (FSH) and luteinizing hormone (LH) than normal.
Effects on Growth and Development
- The X chromosome carries genes important for growth and development, including the SHOX gene.
- Having a single copy of the SHOX gene results in short stature.
- Individuals with Turner syndrome are also predisposed to cardiovascular defects, kidney issues, lymphatic and skeletal abnormalities, and are at higher risk for type II diabetes and hypothyroidism.
Signs and Symptoms
- Signs and symptoms of Turner syndrome vary depending on the age of the person and the proportion of cells with the 45, X karyotype.
- Infants may be born with lymphedema, cystic hygroma, and neck webbing.
- Children with horseshoe kidney are more likely to have urinary tract infections.
- Adolescents may exhibit skeletal abnormalities, such as short stature, broad chest, low-set ears, and cubitus valgus.
- Turner syndrome is also the most common cause of primary amenorrhea, resulting in infertility.
Diagnosis and Treatment
- Karyotype analysis is the only way to diagnose Turner syndrome.
- Other tests, such as ultrasound and fasting blood glucose tests, can help identify specific developmental abnormalities caused by Turner syndrome.
- Treatment typically involves growth hormone therapy in childhood and sex hormone replacement therapy starting at adolescence.
Learn about the least common karyotype in Turner syndrome, where a part of the X chromosome is missing. Discover how errors in meiosis and mitosis can lead to this genetic condition. Test your understanding of genetics and Turner syndrome.
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