Analiza genetskih različic v regulatornih in kodirajočih področjih gena SHOX pri otrocih z nepojasnjeno nizko rastjo

Stritar, Jera (author), Trebušak Podkrajšek, Katarina (mentor), Hovnik, Tinka (comentor)

Nizka rast je pogosto razvojno stanje v otroštvu. Opredeljena je kot telesna višina, ki je manjša od dveh standardnih odklonov (-2 SD) povprečne višine za spol, starost in populacijo. Pojavlja se pri nekaterih motnjah endokrinega sistema, kroničnih sistemskih boleznih, presnovnih in kostnih boleznih ter v sklopu določenih genetskih sindromov. Vseeno pa velik delež nizke rasti ostaja nepojasnjen, kar imenujemo idiopatska ali nepojasnjena nizka rast. Med pogostejšimi genetskimi vzroki nizke rasti so spremembe v regulatornih in kodirajočih področjih gena SHOX. Te naj bi bile glede na tujo literaturo odgovorne tudi za 2-15% primerov nepojasnjene nizke rasti. Gen SHOX se nahaja v psevdoavtosomalni regiji kratke ročice kromosomov X in Y ter ima pomembno vlogo v razvoju okostja. Najpogostejše genetske spremembe gena SHOX so delecije različnega obsega, ki lahko zajemajo sam gen ali pa njegove regulatorne regije. Sledijo duplikacije ter nesmiselne in drugačnosmiselne točkovne spremembe v kodirajočem območju gena. Namen magistrske naloge je bil s sekvenciranjem po Sangerju določiti točkovne spremembe, manjše delecije in insercije, z metodo hkratnega pomnoževanja od ligacije odvisnih sond (MLPA) pa določiti večje spremembe v številu kopij (CNV) gena SHOX v slovenski populaciji otrok z nepojasnjeno nizko rastjo. Dobljene rezultate smo primerjali s podatki iz literature. V raziskavo je bilo vključenih 84 preiskovancev z neznano etiologijo nizke rasti, vodenih na Kliničnem oddelku za endokrinologijo, diabetes in presnovne bolezni ter v genetski ambulanti Pediatrične klinike UKC Ljubljana. Vzročno spremembo v genu SHOX smo odkrili le pri enem preiskovancu, kar predstavlja 1,2% raziskovalne skupine. Na podlagi naše raziskave lahko torej trdimo, da je pojavnost SHOX sprememb v populaciji slovenskih otrok nepojasnjene nizke rasti manjša, kot bi pričakovali glede na podatke v drugih populacijah. Je pa to v skladu z rezultati predhodno opravljene raziskave na manjši skupini slovenskih bolnikov z nepojasnjeno nizko rastjo.

• Language: Slovenian
• Keywords: Nepojasnjena nizka rast, sekvenciranje po Sangerju, MLPA, gen SHOX.
• Work type: Master's thesis/paper
• Organization: FFA - Faculty of Pharmacy
• Year: 2020
• PID: 20.500.12556/RUL-118183
• Publication date in RUL: 26.08.2020

Secondary language

• Language: English
• Title: Analysis of SHOX gene regulatory and coding region variants in pediatric patients with idiopathic short stature

Abstract

Short stature is a common growth disorder in childhood. It is defined as a body height which is two standard deviations (SD) or more below the mean for children of that sex, age and population. It occurs in some endocrine disorders, chronic systemic diseases, metabolic, skeletal and genetic disorders. However, a large part of the cases remains unexplained and is referred to as idiopathic short stature. One of the leading genetic causes of short stature are variants in the regulatory and coding regions of the short stature homeobox-containing gene (SHOX gene). These variants, according to references, are considered to be responsible for 2-15% of cases of idiopathic short stature. SHOX gene is located in the pseudoautosomal region of the short-arm tips of both X and Y chromosomes and is essential for the development of the skeleton. The most common SHOX defects are various deletions, which include the gene itself or its regulatory regions. Less common are duplications, nonsense and missense point mutations in the coding region of the gene. The aim of this study was to detect any sequence variations in the SHOX gene among the Slovenian population of children with idiopathic short stature. Sanger sequencing was used for detection of point mutations, small deletions and insertions. Multiplex ligation-dependent probe amplification (MLPA) was used for the detection of larger copy number variations (CNV). Results obtained in this study were compared to the existing data. 84 children with idiopathic short stature were included in this study. All of them were referred to the Department of Pediatric Endocrinology, Diabetes and Metabolic Diseases or Genetic ambulant at the University Children’s Hospital, University Medical Centre Ljubljana. The disease-causing variant in the SHOX gene was discovered only in one patient, which represents 1,2% of the cohort. According to these results, in the Slovenian population of children with idiopathic short stature SHOX deficiency is less frequent than expected considering existing data from other populations. Nevertheless, this is in concordance with a previous study in a smaller cohort of Slovenian patients with idiopathic short stature.

• Keywords: Idiopathic short stature, Sanger sequencing, MLPA, SHOX gene.