Turner Syndrome, also known as 45,X or Monosomy X, is a genetic disorder that affects females and is characterized by the partial or complete absence of one of the X chromosomes. This leads to a range of developmental and medical issues.
Genetic Cause:
Chromosomal Basis: Turner Syndrome occurs when one of the two X chromosomes normally present in females is missing or structurally altered. This results in a 45,X karyotype instead of the typical 46,XX.
Types of Chromosomal Abnormalities:
Complete Monosomy: One X chromosome is completely missing.
Mosaicism: Some cells have two X chromosomes, while others have only one X chromosome (45,X/46,XX).
X Chromosome Abnormalities: Structural defects such as ring chromosome or isochromosome (where one arm of the X chromosome is duplicated and the other is deleted).
Incidence:
Turner Syndrome occurs in about 1 in 2,500 live female births, making it one of the more common chromosomal disorders.
Clinical Features:
Short Stature: Most individuals with Turner Syndrome are shorter than average.
Gonadal Dysgenesis: Underdeveloped ovaries leading to primary amenorrhea (absence of menstruation) and infertility.
Physical Characteristics:
Webbed neck (extra folds of skin at the neck).
Broad chest with widely spaced nipples.
Low hairline at the back of the neck.
Heart Defects: Congenital heart defects such as bicuspid aortic valve and coarctation of the aorta.
Kidney Abnormalities: Horseshoe kidney or other renal malformations.
Hearing Loss: Increased risk of ear infections and progressive hearing loss.
Lymphatic Issues: Lymphedema (swelling due to lymph fluid) in hands and feet, particularly at birth.
Non-Verbal Learning Disabilities: Difficulties with spatial reasoning, mathematics, and executive functioning.
Diagnosis:
Prenatal Screening: Ultrasound may detect some physical abnormalities, and non-invasive prenatal testing (NIPT) can indicate chromosomal abnormalities.
Diagnostic Testing: Amniocentesis or chorionic villus sampling (CVS) for confirmation.
Postnatal Diagnosis: Physical examination and karyotyping to identify the chromosomal abnormality.
Prognosis:
With appropriate medical care, individuals with Turner Syndrome can lead healthy and productive lives. Lifespan is typically normal, although there may be an increased risk of certain health problems such as cardiovascular disease and osteoporosis.
Management:
Growth Hormone Therapy: Administered to increase final adult height.
Estrogen Replacement Therapy: To induce the development of secondary sexual characteristics and maintain bone health.
Medical Monitoring: Regular check-ups for heart, kidney, and hearing problems.
Psychosocial Support: Counseling and educational support to address learning difficulties and social challenges.
Fertility Treatment: Assisted reproductive technologies can help some women with Turner Syndrome have biological children.