Neuromyopathy with congenital cataracts and glaucoma: A distinct syndrome caused by POLG variants

We identified three non-related patients manifesting a childhood-onset progressive neuromyopathy with congenital cataracts, delayed walking, distal weakness and wasting, glaucoma and swallowing difficulties. Electrophysiology and nerve biopsies showed a mixed axonal and demyelinating neuropathy, while muscle biopsy disclosed both neurogenic and myopathic changes with ragged red fibers, and muscle MRI showed consistent features across patients, with a peculiar concentric disto-proximal gradient of fatty replacement. We used targeted next generation sequencing and candidate gene approach to study these families. Compound biallelic heterozygous variants, p.[(Pro648Arg)]; [(His932Tyr)] and p.[(Thr251Ile),(Pro587Leu)]; [(Arg943Cys)], were found in the three patients causing this homogeneous phenotype. Our report on a subset of unrelated patients, that showed a distinct autosomal recessive childhood-onset neuromyopathy with congenital cataracts and glaucoma, expands the clinical spectrum of POLG-related disorders. It also confirms the association between cataracts and neuropathy with variants in POLG. Early onset cataract is otherwise rare in POLG-related disorders and so far reported only in a few patients with the clinical pattern of distal myopathy or neuromyopathy

Molecular genetic analysis of rare ocular disorders in Roma population from the Czech Republic

The Roma are the largest and most widespread transnational ethnic community. The Czech Republic estimates their 2% representation in its population. Due to the high level of endogamy, the spectrum and frequency of hereditary diseases in the Roma population differ from the majority population. Hereditary eye diseases are one of the most common causes of blindness in younger adults and thus represent a real socio-economic burden. The aim of the thesis was to perform molecular genetic analysis in individuals of Roma origin suffering from hereditary diseases affecting vision, including dual impairments and syndromes, and to determinate the frequency of the detected pathogenic variants in this population. Molecular genetic analysis of 17 families was performed using direct and whole exome sequencing. Within the framework of an international collaboration, the degree of their mutual kinship was calculated using the PLINK program. The frequency of selected variants was determined in a control dataset comprising 156 Roma exomes and genomes. The spectrum of analyzed diseases included various retinal dystrophies, primary congenital glaucoma, Usher syndrome, neuronal ceroid lipofuscinosis, Noonan syndrome, nanophthalmos and congenital cataract, facial dysmorphism and neuropathy. The results of the thesis...Romové jsou největší a nejrozšířenější nadnárodní etnickou komunitou. Česká republika odhaduje jejich 2% zastoupení ve své populaci. Vzhledem k vysoké míře endogamie jsou spektrum a frekvence dědičných onemocnění v romské populaci odlišné od populace většinové. Hereditární onemocnění oka jsou jednou z nejčastějších příčin nevidomosti u dětí a mladších dospělých a představují tak významnou socioekonomickou zátěž. Cílem práce byla molekulárně genetická analýza dědičných onemocnění postihující zrak včetně kombinovaných vad a syndromů u jedinců romského původu a stanovení frekvence detekovaných patogenních variant v této populaci. Molekulárně genetická analýza 17 rodin byla provedena pomocí přímého a celoexomového sekvenování. V rámci mezinárodní spolupráce byla dále stanovena jejich vzájemná míra příbuznosti pomocí programu PLINK. Frekvence vybraných variant byla sledována na kontrolním souboru 156 romských exomů a genomů. Spektrum chorob v analyzovaném souboru zahrnovalo různé dystrofie sítnice, primární kongenitální glaukom, Usherův syndrom, neuronální ceroidní lipofuscinózu, Noonanův syndrom, nanoftalmus a syndrom kongenitální katarakty, faciálního dysmorfismu a demyelinizační neuropatie. Výsledky diplomové práce naznačují, že romská populace žijící na území České republiky má vyšší riziko vzniku...Department of Genetics and MicrobiologyKatedra genetiky a mikrobiologieFaculty of SciencePřírodovědecká fakult

BRCA1 & CTDP1 BRCT Domainomics in the DNA Damage Response

Genomic instability is one of the enabling characteristics of cancer. DNA damage response pathways are important for genomic integrity and cell cycle progression. Defects in DNA damage repair can often lead to cell cycle arrest, cell death, or tumorigenesis. The activation of the DNA damage response includes tightly regulated signaling cascades that involve kinase phosphorylation and modular domains that scaffold phosphorylated motifs to coordinate recruitment of DNA repair proteins. Modular domains are conserved tertiary structures of a protein that can fold, function, and evolve independently from an intact protein. One of the most common modular domains involved in DNA damage repair is the BRCA1 C-Terminal (BRCT) domain. The BRCT domain is approximately 90-100 amino acids long and functions as a scaffolding domain to help recruit DNA damage-related proteins for DNA repair. Mechanisms in which BRCT domains regulate DNA repair have yet to be fully elucidated. Studying protein-protein interactions mediated by these domains can improve our understanding of how BRCT domains function in DNA repair. The goal of this dissertation is to characterize the scaffolding functions of BRCT domains and how their interactions contribute to DNA damage repair pathways dysregulated in cancer. BRCA1, the protein in which the BRCT domain was first identified, is the most well-known cancer susceptibility gene, often mutated in cases of breast and ovarian cancers. Our research has identified that BRCA1 BRCT domain-mediated interactions with the mTORC2 complex disrupt the complex and impair Akt activation, which is critical for cancer cell growth, proliferation, and survival. We have sought to identify how mTORC2 activity may regulate BRCA1 function as a DNA damage regulator and a transcriptional co-activator and contribute to the DNA damage response. We have found that rapamycin treatment increases BRCA1 transcriptional coactivation activity. Also, mTORC2 activity prevents cisplatin-induced cell death. Repression of mTOR signaling reduces gH2AX-BRCA1 foci formation. More importantly, this dissertation work highlights a novel chemotherapeutic strategy of targeting the mTOR pathway for breast cancers with BRCA1 mutations or loss of BRCA1 function. BRCA1 loss sensitizes breast cancer cells to mTOR inhibition. Since the PI3K-mTOR-Akt pathway is upregulated in over 70% of breast cancer cases, breast cancer patients with defective BRCA1 may be ideal candidates for mTOR inhibitor therapeutics. While BRCT domains are largely associated with DNA repair proteins, there are some BRCT domain-containing proteins for which their DNA repair roles are not fully characterized, such as RNA Polymerase II Subunit A C-Terminal Domain Phosphatase 1 (CTDP1). Our research has revealed CTDP1 as a regulator of FANCI in the Fanconi anemia pathway, a pathway important for the repair of interstrand crosslinks (ICLs). CTDP1 influences FANCI chromatin localization, FANDC2 foci formation, sensitivity to ICL-inducing drugs, and homologous recombination repair. In addition, CTDP1 has also been found to be highly expressed in breast cancer cell lines. CTDP1 knockdown in murine mammary orthotopic models prevents tumor formation, thus rendering CTDP1 as a potential target for breast cancer therapeutics. The findings in this dissertation work contribute to our overall understanding of how BRCT domains use their scaffolding function to regulate the DNA damage response. Elucidating the biological importance of these domains can improve our understanding of cancer susceptibilities, tailor chemotherapeutic strategies, and make better informed decisions in cancer therapies