SUPERStudy: TURNER SYNDROME 

Introduction: Turner syndrome is a disorder in females characterized by the absence of all or part of a normal second sex chromosome. Most affected fetuses are spontaneously aborted, accounting for about 10% of all spontaneous abortions. 

Genetic Defect: Patients with the classic syndrome (about 50% of cases) lack one of the two X chromosomes (45,XO karyotype). 

Incidence: 1 in 2500 women

Pathology: Turner syndrome is a sporadic disorder occurring due to nondisjunction or fragmentation of sex chromosomes during gametogenesis or early embryonic development.The most common genetic constitution is 45,X (∼50% of cases) due to complete loss of a sex chromosome in gametogenesis. The next most common genotype includes cell line mosaicism for 45,X/46,XX or 45,X/47,XXX or 45,X/46,XY (∼20% of cases) which occurs as a result of nondisjunction during early embryonic development. 

Clinical Manifestations: 

Mental: Intellectual disabilities, ADHD, and emotional immaturity. 

General: Short stature with a broad chest and widely spread nipples.

Head: High-arched palate, low posterior hairline, and micrognathia 

Mouth: fish mouth (downturned corners of the mouth)

Eyes: Cataracts, corneal opacities, epicanthal folds, strabismus, and ptosis 

Ear: Conductive hearing loss, sensorineural hearing loss, recurrent otitis media, low-set and posteriorly rotated ears.  

Neck: Cystic hygroma of the neck, leading to webbed-neck appearance (pterygium colli).

Cardiac: Coarctation of the aorta; bicuspid aortic valve; aortic dilation or aneurysm, aortic dissection, hypertension, and partial anomalous pulmonary venous return 

Gastrointestinal: Achlorhydria, colon carcinoma, elevated hepatic transaminases, primary biliary cholangitis, and telangiectasias with bleeding. 

Renal: Horseshoe kidney 

Gynecological: hypergonadotropic hypogonadism, infantile genitalia and breasts, primary amenorrhea, two streak ovaries (replacement of ovaries with fibrous strands – ova or follicles)

Extremities: Lymphedema of extremities, cubitus valgus of arms and knock knees, osteopenia, scoliosis, and short fourth metacarpals. 

Endocrine: increased risk for diabetes mellitus, hypertension, Hashimoto thyroiditis, and osteoporosis 

Skin and nails: Hyperconvex nails, keloid formation, and pigmented nevi 

Autoimmune: thyroiditis, IBD, and celiac disease

Oncology: Germ cell tumors such as gonadoblastomas and seminomas 

Diagnosis: 

Prenatal: a chorionic villus sampling (CVS) or amniocentesis. 

At birth: small body size, severe lymphedema, gonadal dysgenesis and loose posterior cervical skin folds

Lab findings: Decreased estrogen production; increased FSH and LH levels 

Blood karyotype: 45,XO (or X chromosome abnormalities or mosaicism); the gold standard test in Turner syndrome.

Imaging: Ultrasound and MRI to investigate cardiac and renal abnormalities.

Treatment: 

Growth hormone to treat short stature; oral androgen oxandrolone 

Estrogen therapy: Transdermal estradiol 

Prognosis: Patients have a decreased life expectancy because of cardiovascular abnormalities. 

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