Intellectual disability, a neuropsychiatric disorder belonging to neurodevelopmental disorders (NDDs), is a multifactorial condition ranging from mild to profound in severity and manifesting either as an isolated trait or as part of a complex syndromic presentation. Recently, techniques of classical (karyotype) and molecular cytogenetics (array-CGH and SNP-array) have been supported by next generation sequencing (NGS) analysis, in particular clinical exome sequencing, also known as Mendeliome sequencing, and whole exome sequencing (WES). These techniques have allowed clinicians to make a definite genetic diagnosis in a portion of patients affected by NDDs, giving information on the natural history of their condition, on the clinical management, as well as on the risk of recurrence for the patient’s relatives, and contributing to the development of networks and databases of support for the international scientific community. In this thesis project we report the diagnostic and analytic workflow carried out for the genetic diagnosis in a cohort of patients affected by isolated and syndromic intellectual disability afferent to “IRCCS - Fondazione Mondino” in Pavia. The integrated application of molecular cytogenetics and WES techniques allowed for the identification of single nucleotide variations (SNVs) in KIF5C, KIF11 and CHD7 genes and copy number variants (CNVs) encompassing the chromosomal regions 16p11.2 and 1q21.1, the latter conditions associated to incomplete penetrance and variable expressivity. In this study, particular emphasis has been put on the genotype-phenotype correlation and the pathogenic mechanisms behind the described conditions.
La disabilità intellettiva, un disturbo neuropsichiatrico appartenente ai disturbi del neurosviluppo (NDDs, Neurodevelopmental Disorders), è una condizione di natura spesso multifattoriale che può variare da un grado lieve a profondo e presentarsi come tratto isolato o inserito in un quadro sindromico più complesso. Recentemente, le tecniche di citogenetica classica (cariotipo) e molecolare (array-CGH e SNP-array) sono state affiancate da metodiche di sequenziamento di nuova generazione (NGS, Next Generation Sequencing), in particolare il sequenziamento dell'esoma clinico, anche noto come Mendelioma, o dell'intero esoma (WES, whole-exome sequencing). Queste tecniche hanno consentito di porre una diagnosi genetica definitiva in una quota di pazienti affetti da NDDs, dando indicazioni sulla storia naturale della condizione, sul management clinico, nonché sul rischio di ricorrenza per i familiari dei pazienti, e contribuendo allo sviluppo di reti e database clinici a supporto della comunità scientifica internazionale. In questo studio di tesi si riporta il workflow diagnostico ed analitico eseguito per la diagnosi genetica in una coorte di pazienti affetti da disabilità intellettiva sindromica ed isolata afferenti all'IRCCS Fondazione Mondino di Pavia. L'impiego integrato di tecniche di citogenetica molecolare e WES ha permesso di identificare sia varianti a singolo nucleotide (SNVs, single nucleotide variants) nei geni KIF5C, KIF11 e CHD7, che variazioni del numero di copie (CNVs, copy number variants) nelle regioni cromosomiche 1q21.1 e 16p11.2, condizioni queste ultime associate a penetranza incompleta ed espressività variabile. Nello studio particolare enfasi è stata rivolta alla correlazione genotipo-fenotipo ed ai meccanismi patogenetici alla base delle condizioni riscontrate.
UN WORKFLOW DIAGNOSTICO INTEGRATO, WHOLE-EXOME SEQUENCING E CARIOTIPO MOLECOLARE, IN PAZIENTI CON DISABILITA’ INTELLETTIVA SINDROMICA ED ISOLATA
POLITANO, DAVIDE
2020/2021
Abstract
Intellectual disability, a neuropsychiatric disorder belonging to neurodevelopmental disorders (NDDs), is a multifactorial condition ranging from mild to profound in severity and manifesting either as an isolated trait or as part of a complex syndromic presentation. Recently, techniques of classical (karyotype) and molecular cytogenetics (array-CGH and SNP-array) have been supported by next generation sequencing (NGS) analysis, in particular clinical exome sequencing, also known as Mendeliome sequencing, and whole exome sequencing (WES). These techniques have allowed clinicians to make a definite genetic diagnosis in a portion of patients affected by NDDs, giving information on the natural history of their condition, on the clinical management, as well as on the risk of recurrence for the patient’s relatives, and contributing to the development of networks and databases of support for the international scientific community. In this thesis project we report the diagnostic and analytic workflow carried out for the genetic diagnosis in a cohort of patients affected by isolated and syndromic intellectual disability afferent to “IRCCS - Fondazione Mondino” in Pavia. The integrated application of molecular cytogenetics and WES techniques allowed for the identification of single nucleotide variations (SNVs) in KIF5C, KIF11 and CHD7 genes and copy number variants (CNVs) encompassing the chromosomal regions 16p11.2 and 1q21.1, the latter conditions associated to incomplete penetrance and variable expressivity. In this study, particular emphasis has been put on the genotype-phenotype correlation and the pathogenic mechanisms behind the described conditions.È consentito all'utente scaricare e condividere i documenti disponibili a testo pieno in UNITESI UNIPV nel rispetto della licenza Creative Commons del tipo CC BY NC ND.
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https://hdl.handle.net/20.500.14239/13536