Taylor_Speroff's Clinical Gynecologic Endocrinology and Infe

286 Section II • Clinical Endocrinology

observed, even in young children with Turner syndrome. 508,509 Idiopathic hypertension also is common, even in the absence of any apparent renal or cardiac malformations. 510,511 Patients with Turner syndrome are predisposed to devel oping osteoporosis, primarily due to ovarian failure but pos sibly also relating to haploinsufficiency for genes affecting bone located on the X chromosome. 512,513 Many also have ocular abnormalities, including amblyopia, strabismus, pto sis, hypertelorism, epicanthus, farsightedness, and red-green color blindness. 514–516 The prevalence of endocrine diseases such as hypothyroidism and diabetes is increased and, for hypothyroidism, correlates with the karyotype (X isochro mosome, 38%; 45,X, 14%; other, 6%). 517 Celiac disease, hearing loss, and liver function abnormalities also are more common in patients with Turner syndrome. 518–521 Patients with Turner syndrome typically have normal intelligence. 522 The rare patient having a small X-ring chro mosome may have severe mental retardation, because the ring chromosome does not undergo X-inactivation. 523,524 Nonetheless, formal evaluation of intellectual, learning, and motor skills generally is recommended before enrollment in school. 525 Attention deficit/hyperactivity disorder (ADHD) 526 and problems with visual-spatial organization 527 are more common in girls with Turner syndrome. Overall mortality is increased approximately threefold, relating primarily to circulatory disease, diabetes, and liver and renal disease. 528 Although overall cancer risk in women with Turner syndrome is similar to that in the general pop ulation, the incidence of CNS tumors, bladder cancer, and endometrial cancer may be increased, and the risk of breast cancer is decreased 529 (Figure 8.13) . Diagnosis The diagnosis of Turner syndrome sometimes is inciden tal, discovered when prenatal CVS or amniocentesis is per formed for advanced maternal age or prenatal testing raises

suspicion for chromosomal anomalies. 530 Diagnosis can be made at birth but often is delayed until childhood or ado lescence. Neonates frequently exhibit lymphedema of the hands and feet, a webbed neck, nail dysplasia, a high pal ate, or short fourth metacarpals; short stature and delayed puberty are the later diagnostic keys. 531 Therefore, karyotyp ing is recommended for all girls with unexplained short stature, delayed puberty, a webbed neck, lymphedema, or aortic coarctation and should be considered for those with two or more phenotypic features suggesting the diagnosis. Karyotype should include an examination of at least 30 cells, to detect significant mosaicism (e.g., 45,X/46,XX; 45,X/46,XY). For those with a suspicious phenotype but hav ing a normal lymphocyte karyotype, a second tissue (e.g., skin fibroblasts) should be examined to exclude tissue-specific mosaicsm. 532 Patients with Turner syndrome having a chro mosomal fragment of uncertain origin and those exhibit ing any evidence of virilization also should be evaluated specifically using FISH and Y chromosome-specific probes, because those having all or part of a Y (approximately 5%) are at increased risk for developing gonadoblastoma. 533–537 Clinical Management The spectrum of medical problems in patients with Turner syndrome and their health implications require specific evaluation and periodic monitoring, as described in detail in Chapter 10. 534 In brief summary, evaluation should include periodic echocardiography (or MRI if required), renal ultrasonography, thyroid function studies, a complete blood count, fasting glucose, lipid profile, and renal and liver function tests, antiendomysial antibodies (to detect celiac disease), and audiometry. Those with coarctation of the aorta should undergo surgery for its correction, and those with other anomalies must be monitored carefully. Hypertension, hypothyroidism, and hearing and visual problems also require specific treatment.

Xp

Short stature

Pseudoautosomal region

Yp

Pseudoautosomal region

SRY Sex determining region Genes that prevent short stature & stigmata of Turner syndrome Centromere Genes that affect spermatogenesis and the predisposition to gonadoblastoma in dysgenetic gonads

Genes responsible for Turner syndrome and short stature

Mental retardation

X-linked icthyosis

Androgen receptor

Kallmann syndrome

Gene(s) that affect ovarian function (and some stigmata of Turner syndrome)

Heterochromatic region (genetically inactive) Copyright © 2019 Wolters Kluwer, Inc. Unauthorized reproduction of the content is prohibited.

Yq

Xq

FIGURE 8.13