High-Yield Clinical Features of Turner Syndrome
Turner syndrome (45,X) presents with a characteristic constellation of features dominated by short stature, primary amenorrhea with ovarian dysgenesis, and cardiovascular malformations that significantly increase mortality risk, particularly from aortic dissection. 1
Cardiovascular Features (Most Critical for Mortality)
Cardiovascular abnormalities are the primary cause of premature death in Turner syndrome and occur in approximately 50% of patients. 1, 2
Structural Cardiac Abnormalities
- Bicuspid aortic valve (BAV) occurs in 15-30% of patients and represents the most common congenital cardiac defect 1
- Aortic coarctation is present in 7-18% of patients 1
- Ascending aortic dilation affects approximately 33% of patients 1
- Hypoplastic left heart and other complex congenital heart defects occur less commonly 1
Aortic Dissection Risk (Critical Pitfall)
- Aortic dissection occurs at younger ages and smaller absolute aortic diameters than in the general population due to characteristic short stature 1, 3, 2
- Type A dissection occurs in 85% of cases, Type B in 15% 1
- Risk factors include: aortic dilation, hypertension, BAV, and aortic coarctation 1
- Critical error: Using absolute aortic measurements without indexing to body size critically underestimates dissection risk 1, 3, 4
Phenotypic/Dysmorphic Features
Classic Physical Stigmata
- Short stature is universal or near-universal (present in 100% of classical monosomy, 77.8% in mosaic forms) 1, 5
- Webbed neck (pterygium colli) is a classic visible feature 1, 3
- Lymphedema of hands and feet, particularly prominent in infancy 1, 3
- Low posterior hairline 6, 5
- Broad chest with widely spaced nipples 6, 5
- Cubitus valgus (increased carrying angle of elbows) 6
- Short 4th and 5th metacarpals 6
- Multiple pigmented nevi 6
Reproductive/Endocrine Features
Gonadal Dysfunction
- Primary amenorrhea occurs in 100% of classical monosomy (45,X) and 63.2% of mosaic forms 5
- Ovarian dysgenesis with hypergonadotropic hypogonadism is characteristic 3, 7
- Premature ovarian failure and infertility affect the majority of patients 8, 7
- Spontaneous pregnancy is rare (more common in mosaic forms) but carries substantially increased cardiovascular risks 6, 7
Associated Endocrine Disorders
- Hypothyroidism occurs with increased frequency and requires regular screening 3, 8
- Type 1 and Type 2 diabetes mellitus risk is increased 8, 7
- Osteoporosis risk is elevated 8, 7
Prenatal Presentation
Fetal Findings
- Cystic hygroma is associated with 50-80% of prenatally detected Turner syndrome cases, resulting from lymphatic dysplasia 3
- Nonimmune hydrops fetalis may develop secondary to lymphatic dysplasia and cardiovascular malformations 3
Genetic Considerations
Karyotype Variations
- Classical monosomy 45,X accounts for approximately 50% of cases 6, 5
- Mosaicism (45,X/46,XX, 45,X/47,XXX, and other variants) affects approximately 55% of patients and significantly influences phenotype 4, 6
- Y chromosome material must be identified as it confers increased gonadoblastoma risk requiring gonadectomy 4
Other Associated Conditions
Additional Organ System Involvement
- Renal anomalies occur with increased frequency 1, 5
- Recurrent otitis media is common 5
- Autoimmune disorders have increased prevalence 8, 7
- Intellectual performance is typically within normal range, though specific learning disabilities may occur 8
Critical Clinical Pitfalls to Avoid
Failure to perform baseline cardiac MRI at diagnosis misses important structural abnormalities not visible on echocardiography alone 3, 4
Inadequate surveillance frequency for patients with aortic size index (ASI) >2.3 cm/m² (requires at least annual imaging, not every 5-10 years) 1, 3, 2
Assuming normal cardiovascular anatomy based on physical examination alone when up to 50% have cardiovascular defects requiring imaging 4, 2
Pregnancy without mandatory pre-conception cardiovascular evaluation given substantially increased aortic dissection risk 3, 2