Cancer is a complex disease resulting from the accumulation of genetic dysfunctions. Tumor heterogeneity causes the molecular variety that divergently controls responses to chemotherapy, leading to the recurrent problem of cancer reappearance. For many decades, efforts have focused on identifying essential tumoral genes and cancer driver mutations. More recently, prompted by the clinical success of the synthetic lethality (SL)-based therapy of the PARP inhibitors in homologous recombinant deficient tumors, scientists have centered their novel research on SL interactions (SLI). The state of the art to find new genetic interactions are currently large-scale forward genetic CRISPR screens. CRISPR technology has rapidly evolved to be a common tool in the vast majority of laboratories, as tools to implement CRISPR screen protocols are available to all researchers. Taking advantage of SLI, combinatorial therapies have become the ultimate model to treat cancer with lower toxicity, and therefore better efficiency. This review explores the CRISPR screen methodology, integrates the up-to-date published findings on CRISPR screens in the cancer field and proposes future directions to uncover cancer regulation and individual responses to chemotherapy.

Background: About 40% of RAS/BRAF wild-type metastatic colorectal cancer (mCRC) patients undergoing anti-EGFR-based therapy have poor outcomes. Treatment failure is not only associated with poorer prognosis but higher healthcare costs. Our aim was to identify novel somatic genetic variants in the primary tumor and assess their effect on anti-EGFR response. Patients and Methods: Tumor (somatic) and blood (germline) DNA samples were obtained from two well-defined cohorts of mCRC patients, those sensitive and those resistant to EGFR blockade. Genetic variant screening of 43 EGFR-related genes was performed using targeted next-generation sequencing (NGS). Relevant clinical data were collected through chart review to assess genetic results. Results: Among 61 patients, 38 were sensitive and 23 were resistant to treatment. We identified eight somatic variants that predicted non-response. Three were located in insulin-related genes (I668N and E1218K in IGF1R, T1156M in IRS2) and three in genes belonging to the LRIG family (T152T in LRIG1, S697L in LRIG2 and V812M in LRIG3). The remaining two variants were found in NRAS (G115Efs*46) and PDGFRA (T301T). We did not identify any somatic variants related to good response. Conclusions: This study provides evidence that novel somatic genetic variants along the EGFR-triggered pathway could modulate the response to anti-EGFR drugs in mCRC patients. It also highlights the influence of insulin-related genes and LRIG genes on anti-EGFR efficacy. Our findings could help characterize patients who are resistant to anti-EGFR blockade despite harboring RAS/BRAF wild-type tumors.

Background: Initial Whole Exome Sequencing frequently fails to resolve rare disease cases. Bioinformatic reanalysis of existing genomic data utilizes advancing knowledge to enhance diagnosis without additional testing. This study investigated six patients with clinical features consistent with Fanconi Anemia but negative chromosomal breakage tests, whose initial genetic analyses were inconclusive. Results: Whole Exome Sequencing data from these patients (collected 2005–2009) underwent comprehensive reanalysis, including single nucleotide variants, insertions/deletions, and copy number variants across genes beyond those typically associated with Fanconi Anemia. Telomere length was assessed via monochrome multiplex quantitative PCR. Reanalysis identified clinically significant variants in two patients (33.3% yield): one harboured a heterozygous pathogenic loss-of-function variant in the Diamond-Blackfan anemia gene RPL5, while the second exhibited compound heterozygous variants in the TERT gene, indicative of dyskeratosis congenita. Conclusions: This study underscores the clinical value of reanalyzing existing genomic data in unresolved suspected genetic disorders, even when phenotype-specific assays are negative. The 33.3% diagnostic yield aligns with gains from larger reanalysis studies (10–25%). Systematic reassessment after sufficient time (24 + months) for genomic advancements offers a cost-effective diagnostic approach for long-undiagnosed cases, highlighting the dynamic nature of genomic interpretation as gene-disease understanding evolves.

Purpose: Carrier screening identifies individuals at risk of transmitting autosomal recessive or X-linked recessive conditions, supporting informed reproductive decisions. Despite international recommendations for universal carrier screening, integration into public healthcare systems remains limited. This study evaluated the feasibility of implementing a carrier screening program in Spain’s public health system. Methods: Non-pregnant women aged 18 to 38 with reproductive intent were recruited through text messages sent from a primary care center, along with their partners. A sequential screening approach was used: women underwent a 351-gene massively parallel sequencing panel and complementary tests, while male partners were tested only if their partner carried autosomal recessive variants. Specific genetic counselling was provided, and emotional responses were assessed through pre- and post-test questionnaires. Results: Of 518 candidates contacted, 400 (77%) responded positively and 152 couples (50.8% of those eligible) enrolled. Among 218 individuals screened, 62% (135) carried at least one pathogenic variant. Six carrier couples (4%) were identified as being at reproductive risk of non-syndromic hearing loss ( GJB2 , 2 couples), cystic fibrosis ( CFTR ), Stargardt disease and retinitis pigmentosa ( ABCA4 ), Smith-Lemli-Opitz syndrome ( DHCR7 ), and Fabry disease ( GLA ). Of four couples followed post-disclosure, 75% opted for in vitro fertilization with preimplantation genetic testing or prenatal diagnosis. Prevention of severe genetic conditions was the most frequently reported motivation for participation. Conclusions: This study proves the feasibility and clinical utility of carrier screening within a public healthcare system. Our findings demonstrate high participation rates, clinical relevance through the identification of 4% of carrier couples, and strong motivation among participants to prevent the transmission of severe genetic conditions.