Definition (Am Fam Physician 2007;76:405; Clin Pediatr (Phila) 2006;45:301)
• Partial or complete absence of X chromosome, 45 X karyotype
• 50 per 100,000 live female births
Diagnosis (Nat Clin Pract Endocrinol Metab 2005;1:41)
• Consider in girls with short stature (2 SD below mean height for age), primary amenorrhea, lack of breast development, delayed puberty
• Consider in fetus w/ hydrops, ↑ nuchal translucency, cystic hygroma, or lymphedema
• Dx made with karyotyping → chromosomal analysis of 30 peripheral lymphocytes
• 50% w/ missing X chromosome in all cells studied, others w/ 45, X/46, XX mosaic
Clinical Manifestations
• Risk of congenital heart defects → 75% with either coarctation of the aorta or bicuspid aortic valve. Risk of progressive aortic root dilation or dissection
• Risk of cong lymphedema, renal malform, hearing loss, osteoporosis, obesity, and diabetes
• Normal IQ, although may have difficulty w/ nonverbal, social, and psychomotor skills
• Physical exam: Misshapen or rotated ears, low posterior hairline, webbed neck, broad chest with widely spaced nipples and cubitus valgus, shortened 4th metacarpal
• Almost all are infertile
Management (Endocrine 2011 PMID 22147393)
Treat short stature with GH therapy through bone age of 14 yo.
• Estrogen in adolescence for pubertal development and prevention of osteoporosis with Ca + Vit D. Continue throughout life
• Hearing tests, pediatric optho for hyperopia and strabismus, regular dental visits
• Echocardiogram to r/o congenital heart defects, 4 ext BPs to follow for coarctation
• Renal ultrasound for renal malformations
• >4 yo r/o celiac with tissue transglutaminase immunoglobulin A & rpt q2–4yr
• Annual TFTs, LFTs, fasting lipids, and glucose
• If Y chromosome is present, 12% risk of gonadoblastoma; must refer for removal
Complications
Strabismus, hearing loss, recurrent otitis media, tooth anomalies, renal malform, autoimmune thyroiditis, celiac dz, congenital hip dysplasia, and scoliosis. ↑ risk colon, breast, and endometrial Ca (from estrogen use). Aortic dissection or rupture especially w/ pregnancy.