Mitochondria are subcellular organelles involved in essential cellular functions, including cytosolic calcium regulation, cell apoptosis, and reactive oxygen species production. They are the site of important biochemical pathways, including the tricarboxylic acid cycle, parts of the ureagenesis cycle, or haem synthesis. Mitochondria are responsible for the majority of cellular ATP production through OXPHOS. Mitochondrial dysfunction has been associated with metabolic pathologies such as diabetes, obesity, hypertension, neurodegenerative diseases, cellular aging, and cancer. In this article, we describe the pathophysiological changes in, and mitochondrial role of, metabolic disorders (diabetes, obesity, and cardiovascular disease) and their correlation with oxidative stress. We highlight the genetic changes identified at the mtDNA level. Additionally, we selected several representative biomarkers involved in oxidative stress and summarize the progress of therapeutic strategies.

Over the past 40 years, the 5-years-overall survival rate of pediatric cancer reached 75–80%, and for acute lymphoblastic leukemia (ALL), exceeded 90%. Leukemia continues to be a major cause of mortality and morbidity for specific patient populations, including infants, adolescents, and patients with high-risk genetic abnormalities. The future of leukemia treatment needs to count better on molecular therapies as well as immune and cellular therapy. Advances in the scientific interface have led naturally to advances in the treatment of childhood cancer. These discoveries have involved the recognition of the importance of chromosomal abnormalities, the amplification of the oncogenes, the aberration of tumor suppressor genes, as well as the dysregulation of cellular signaling and cell cycle control. Lately, novel therapies that have already proven efficient on relapsed/refractory ALL in adults are being evaluated in clinical trials for young patients. Tirosine kinase inhibitors are, by now, part of the standardized treatment of Ph+ALL pediatric patients, and Blinatumomab, with promising results in clinical trials, received both FDA and EMA approval for use in children. Moreover, other targeted therapies such as aurora-kinase inhibitors, MEK-inhibitors, and proteasome-inhibitors are involved in clinical trials that include pediatric patients. This is an overview of the novel leukemia therapies that have been developed starting from the molecular discoveries and those that have been applied in pediatric populations.

The diagnosis and management of fragile X syndrome (FXS) have significantly improved in the last three decades, although the current diagnostic techniques are not yet able to precisely identify the number of repeats, methylation status, level of mosaicism, and/or the presence of AGG interruptions. A high number of repeats (>200) in the fragile X messenger ribonucleoprotein 1 gene (FMR1) results in hypermethylation of promoter and gene silencing. The actual molecular diagnosis is performed using a Southern blot, TP-PCR (Triplet-Repeat PCR), MS-PCR (Methylation-Specific PCR), and MS-MLPA (Methylation-Specific MLPA) with some limitations, with multiple assays being necessary to completely characterise a patient with FXS. The actual gold standard diagnosis uses Southern blot; however, it cannot accurately characterise all cases. Optical genome mapping is a new technology that has also been developed to approach the diagnosis of fragile X syndrome. Long-range sequencing represented by PacBio and Oxford Nanopore has the potential to replace the actual diagnosis and offers a complete characterization of molecular profiles in a single test. The new technologies have improved the diagnosis of fragile X syndrome and revealed unknown aberrations, but they are a long way from being used routinely in clinical practice.

Wolf–Hirschhorn syndrome (WHS), a rare disorder determined by distal 4p deletion, is characterized by a pre and postnatal growth retardation, hypotonia, intellectual disability, epilepsy, craniofacial dysmorphism, and congenital fusion anomalies. The clinical aspects are dependent on the deletion’ size. Our aim was to identify rare specific characteristics in a cohort of seven cases with 4p deletion and to assess the utility of Multiplex ligation-dependent probe amplification (MLPA) (cheap and sensitive test)—combined kits—as a diagnostic test and selection tool for cases that require other investigations (chromosomal microarray analysis—CMA, karyotype). For all cases we conducted a clinical examination with the main features identified: facial dysmorphism, intellectual disability, postnatal development delay, cardiac defects and hypotonia. In some cases, we observed seizures, structural brain abnormalities, immunodeficiencies, and renal anomalies. Prenatal growth retardation was detected in a relatively small number of cases, but postnatal growth failure was a constant feature. In all cases, the clinical diagnosis was confirmed by genetic analyses: karyotype and/or MLPA. In conclusion, renal and brain defects, as well as immunodeficiency are rare manifestations and should be looked for. Although CMA is the standard test, in our experience, MLPA is also a reliable screening method as the identified cases were either confirmed by MLPA or selected for further investigations.

The most frequent microdeletion, 22q11.2 deletion syndrome (22q11.2DS), has a wide and variable phenotype that causes difficulties in diagnosis. 22q11.2DS is a contiguous gene syndrome, but due to the existence of several low-copy-number repeat sequences (LCR) it displays a high variety of deletion types: typical deletions LCR A–D—the most common (~90%), proximal deletions LCR A–B, central deletions (LCR B, C–D) and distal deletions (LCR D–E, F). Methods: We conducted a retrospective study of 59 22q11.2SD cases, with the aim of highlighting phenotype–genotype correlations. All cases were tested using MLPA combined kits: SALSA MLPA KIT P245 and P250 (MRC Holland). Results: most cases (76%) presented classic deletion LCR A–D with various severity and phenotypic findings. A total of 14 atypical new deletions were identified: 2 proximal deletions LCR A–B, 1 CES (Cat Eye Syndrome region) to LCR B deletion, 4 nested deletions LCR B–D and 1 LCR C–D, 3 LCR A–E deletions, 1 LCR D–E, and 2 small single gene deletions: delDGCR8 and delTOP3B. Conclusions: This study emphasizes the wide phenotypic variety and incomplete penetrance of 22q11.2DS. Our findings contribute to the genotype–phenotype data regarding different types of 22q11.2 deletions and illustrate the usefulness of MLPA combined kits in 22q11.2DS diagnosis.

Background/Objectives: Ulcerative colitis is a chronic inflammatory bowel disease whose incidence is steadily growing worldwide. The interactions between host genetic susceptibility, gut microbiota and environmental factors determine the onset and relapsing evolution of ulcerative colitis, making it a multifactorial disorder. Methods: A narrative review was conducted to synthesize the available literature on the genes and mechanisms related to ulcerative colitis. Results: The most important independent risk factor is genetics and the candidate genes are associated with inflammation, immune regulation and epithelial permeability. Multiple GWAS have already identified candidate genes and their polymorphisms implicated in ulcerative colitis pathogenesis. Genetic susceptibility is conferred by predisposing variants influencing disease onset and progression, as well as by epigenetic modifications (DNA methylation, microRNAs). Conclusions: This review summarizes the interactions between the functional products encoded by genes linked to ulcerative colitis and immunological factors revealing their common mechanisms.