文档介绍：《特纳综合征》
性发育疾病概念及基本分类介绍
特纳综合征概述
症状和体征
诊断
核型-表型关系
治疗
性发育疾病(Disorders of sex development DSD)
是性决定和性分化异常的一组异质s
Visual impairments
Ear infections and hearing loss
High blood pressure
Weak bones
标准型 45，XO 病人有女性表现，但身材矮小、原发闭经、不孕、智力一般正常或稍差，常合并有颅面（蹼颈）、四肢（肘外翻）及心血管方面的畸形，性腺萎缩，可退化成“索状性腺”，第二性征发育不良。
其发病机制为：女性完整的有功能的两条 X 染色体是维持女性性腺发育及正常卵巢功能所必须的。
Lyon 假说认为 46，XX 中的一条 X 染色体失活
TS 患者表型不是 X 单体造成的（45，XO 缺失的是失活的X），这也是 45，XO 能存活的原因。
但失活的 X 染色体并非所有的基因都失活，拟常染色体区（PAR pseudo autosomal region）的基因并不失活，这些未失活的基因在性腺发育的调控中可能发挥着作用。如果基因的数量有了改变，那么基因的产物（如酶、肽链等）的量也随之发生相应改变，即产生基因的剂量效应，因而 X 染色体数目减少、缺失、结构异常都将由于基因的单倍剂量而导致女性性征的异常。
Diagnosis of TS
Prenatal diagnosis
the finding of fetal edema on ultrasonography;
abnormal levels of screening of maternal serum (triple screening)
abnormal results of fetal karyotyping performed because of advanced maternal age
available data suggest that prenatal cytogenetic diagnosis of TS in the absence of abnormal fetal ultrasound has a high false positive rate and seems to be a poor predictor of clinical outcome
Postnatal diagnosis
newborns :puffy hands and feet or redundant nuchal skin; should be suspected in any newborn girl with edema or hypoplastic left heart or coarctation of the aorta
in midchildhood :short stature; primary or secondary amenorrhea
Mosaicism I
In routine karyotyping, 20 cells are counted
(to detect mosaicism at a level of about 5 percent) (Mosaicism for a second, normal 46,XX cell population is about 15 percent )
the detection of a normal cell lineage in fewer than 5 percent of cells does not change the prognosis or the management
if the diagnosis of Turner’s syndrome is suspected clinically but the result of routine testing is normal, increasing the number of cells counted to 100 and performing a skin biopsy for karyotyping of fibroblasts are indicated to rule out mosaicism or an abnormal cell lineage
mosaicism for a cell population with a Y chromosome : at increased risk for gonadoblastoma (risk, 7 to 30 percent) in thei