Capkova Pavlina, Capkova Zuzana, Rohon Peter, Adamová Katerina, Zapletalova Jirina
Department of Medical Genetics, University Hospital Olomouc, Olomouc, Czech Republic.
Department of Medical Genetics, Faculty of Medicine and Dentistry, Palacky University Olomouc, Olomouc, Czech Republic.
PeerJ. 2020 Nov 17;8:e10236. doi: 10.7717/peerj.10236. eCollection 2020.
mutations have previously been described as causes of Léri-Weill dyschondrosteosis (LWD), Langer mesomelic dysplasia (LMD), and idiopathic short stature. The loss of X chromosome-Turner syndrome or mosaic 45,X/46,XX or 46,XY-also leads to the heterozygous loss of in patients with short stature only or with features similar to LWD. The aim of this study was to assess the efficacy of the targeted screening for variants, which involved different methods in the laboratory analysis of short stature. We determined the significance and positive predictive value of short stature for the detection of variants.
Targeted screening for variants in involving MLPA, sequencing, karyotyping and FISH was performed in the short stature cohort ( = 174) and control cohort ( = 91). The significance of short stature and particular characteristics for the detection of variants was determined by Fisher's exact test, and the probability of mutation occurrence was calculated using a forward/stepwise logistic regression model.
In total, 27 and 15 variants influencing were detected in the short stature and control cohorts, respectively ( > 0.01). Sex chromosome aberrations and pathogenic CNV resulting in diagnosis were detected in eight (4.6%) and five (2.9%) patients of the short stature group and three (3.3%) and one (1.1%) individuals of the control group. VUS variants were discovered in 14 (8.0%) and 11 (12.1%) individuals of the short stature and control groups, respectively. MLPA demonstrated the detection rate of 13.22%, and it can be used as a frontline method for detection of aberrations involving . However, only mosaicism of monosomy X with a higher frequency of monosomic cells could be reliably discovered by this method. Karyotyping and FISH can compensate for this limitation; their detection rates in short stature group were 3.55% and 13.46% ( = 52), respectively. FISH proved to be more effective than karyotyping in the study as it could reveal cryptic mosaics in some cases where karyotyping initially failed to detect such a clone. We suggest adding FISH on different tissue than peripheral blood to verify sex-chromosome constitution, especially in cases with karyotypes: 45,X; mosaic 45,X/46,XX or 46,XY; 46,Xidic(Y) detected from blood; in children, where mosaic 45,X was detected prenatally but was not confirmed from peripheral blood. The correlation of short stature with the occurrence of mutations was insignificant and short stature demonstrates a low positive predictive value-15.5% as unique indicator for mutations. The typical skeletal signs of LWD, including Madelung deformity and disproportionate growth, positively correlate with the findings of pathogenic variants ( < 0.01) by Fisher's exact test but not with the findings of VUS variants in which are more prevalent in the individuals with idiopathic short stature or in the individuals with normal height.
此前已将突变描述为勒里-韦伊软骨发育不全（LWD）、朗格中肢发育不全（LMD）和特发性身材矮小的病因。X染色体丢失——特纳综合征或嵌合体45,X/46,XX或46,XY——也会导致仅身材矮小或具有与LWD相似特征的患者中 杂合性丢失。本研究的目的是评估针对 变异体的靶向筛查的有效性，该筛查在身材矮小的实验室分析中涉及不同方法。我们确定了身材矮小对于检测 变异体的意义和阳性预测值。
在身材矮小队列（n = 174）和对照队列（n = 91）中对涉及多重连接依赖探针扩增（MLPA）、测序、核型分析和荧光原位杂交（FISH）的 变异体进行靶向筛查。通过费舍尔精确检验确定身材矮小和特定特征对于检测 变异体的意义，并使用向前/逐步逻辑回归模型计算 突变发生的概率。
在身材矮小队列和对照队列中分别总共检测到27个和15个影响 的变异体（P > 0.01）。身材矮小组的8名（4.6%）和5名（2.9%）患者以及对照组的3名（3.3%）和1名（1.1%）个体中检测到导致诊断的性染色体畸变和致病性拷贝数变异（CNV）。在身材矮小组和对照组中分别有14名（8.0%）和11名（12.1%）个体发现了意义未明的变异体（VUS）。MLPA显示出13.22%的检出率，它可作为检测涉及 的畸变的一线方法。然而，只有具有较高频率单体细胞的单体X嵌合体可通过该方法可靠地发现。核型分析和FISH可弥补这一局限性；它们在身材矮小组中的检出率分别为3.55%和13.46%（n = 52）。在本研究中，FISH被证明比核型分析更有效，因为在某些核型分析最初未能检测到此类克隆的情况下，它可以揭示隐匿性嵌合体。我们建议在不同于外周血的组织上进行FISH以验证性染色体组成，特别是在核型为：45,X；嵌合体45,X/46,XX或46,XY；从血液中检测到46,Xidic(Y)的病例中；在产前检测到嵌合体45,X但未从外周血中得到证实的儿童中。身材矮小与 突变发生的相关性不显著，身材矮小作为 突变的唯一指标显示出较低的阳性预测值——15.5%。LWD的典型骨骼体征，包括马德隆畸形和不成比例生长，通过费舍尔精确检验与致病性 变异体的发现呈正相关（P < 0.01），但与 中VUS变异体的发现不相关，这些变异体在特发性身材矮小个体或身高正常个体中更普遍。
