What is the difference between Turner's syndrome and Monosomy X (45,X)?

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From the Guidelines

Turner syndrome and monosomy X are essentially the same genetic condition, with no difference between them, as they refer to the complete or partial absence of one sex chromosome in a phenotypic female, most commonly 45, X. This condition affects only females and causes characteristic physical features, including short stature, webbed neck, broad chest, low hairline, and reproductive issues, including infertility 1. The most recent guidelines recommend that patients with Turner syndrome undergo cardiac imaging to evaluate for congenital heart and aortic defects, and to determine aortic diameters, due to the increased risk of aortic dissection 1.

Key Characteristics

  • Short stature and ovarian failure are the most prevalent findings in Turner syndrome
  • Women with Turner syndrome have an increased cardiovascular mortality rate from both structural and ischemic heart disease, especially aortic dissection
  • Between 10% and 25% of patients with Turner syndrome have a bicuspid aortic valve, and aortic coarctation is present in approximately 8% of patients 1
  • The condition occurs in approximately 1 in 2,500 female births and results from the complete or partial absence of the second sex chromosome

Management and Treatment

  • Treatment typically includes growth hormone therapy starting in childhood to improve height, and estrogen replacement therapy beginning at puberty to promote development of secondary sexual characteristics
  • Patients with Turner syndrome require regular surveillance imaging with TTE or MRI to evaluate the aorta, every 5 years in children and every 10 years in adults, as well as before planning a pregnancy 1
  • Surgical intervention to replace the aortic root, ascending aorta, or both may be considered in patients with Turner syndrome who have an ASI of ≥2.5 cm/m2 plus risk factors for aortic dissection 1

From the Research

Definition and Characteristics

  • Turner syndrome is a rare condition in women associated with either complete or partial loss of one X chromosome, often in mosaic karyotypes 2.
  • It is characterized by short stature, delayed puberty, ovarian dysgenesis, hypergonadotropic hypogonadism, infertility, congenital malformations of the heart, endocrine disorders, osteoporosis, and autoimmune disorders 2, 3.

Monosomy X

  • Monosomy X refers to the presence of only one X chromosome, which is a characteristic of Turner syndrome 3.
  • Turner syndrome is a neurogenetic disorder characterized by partial or complete monosomy-X 3.

Difference between Turner Syndrome and Monosomy X

  • Turner syndrome and monosomy X are often used interchangeably, but monosomy X is a more general term that refers to the presence of only one X chromosome 3.
  • Turner syndrome is a specific condition that results from monosomy X and is associated with a range of physical and medical features, including estrogen deficiency, short stature, and increased risk for several diseases 2, 3.

Clinical Features and Management

  • Individuals with Turner syndrome commonly exhibit cardiovascular, endocrine, renal, reproductive, and/or psychosocial abnormalities, among other conditions 4.
  • Management of Turner syndrome includes growth hormone therapy, hormone replacement therapy, and multidisciplinary approaches to patient care 2, 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Turner syndrome: mechanisms and management.

Nature reviews. Endocrinology, 2019

Research

Turner syndrome.

Child and adolescent psychiatric clinics of North America, 2007

Research

Sex hormone replacement therapy for individuals with Turner syndrome.

American journal of medical genetics. Part C, Seminars in medical genetics, 2019

Research

Growth hormone therapy in Turner syndrome.

Pediatric endocrinology reviews : PER, 2012

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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