Evaluation of a whole-exome sequencing pipeline and benchmarking of causal germline variant prioritizers.

Most causal variants of Mendelian diseases are exonic. Whole-exome sequencing (WES) has become the diagnostic gold standard, but causative variant prioritization constitutes a bottleneck. Here we assessed an in-house sample-to-sequence pipeline and benchmarked free prioritization tools for germline causal variants from WES data. WES of 61 unselected patients with a known genetic disease cause was obtained. Variant prioritizations were performed by diverse tools and recorded to obtain a diagnostic yield when the causal variant was present in the first, fifth, and 10th top rankings. A fraction of causal variants was not captured by WES (8.2%) or did not pass the quality control criteria (13.1%). Most of the applications inspected were unavailable or had technical limitations, leaving nine tools for complete evaluation. Exomiser performed best in the top first rankings, while LIRICAL led in the top fifth rankings. Based on the more conservative top 10th rankings, Xrare had the highest diagnostic yield, followed by a three-way tie among Exomiser, LIRICAL, and PhenIX, then followed by AMELIE, TAPES, Phen-Gen,  AIVar, and VarNote-PAT. Xrare, Exomiser, LIRICAL, and PhenIX are the most efficient options for variant prioritization in real patient WES data.

Clinical and molecular diagnosis of non-phosphomannomutase 2 N-linked congenital disorders of glycosylation in Spain.

The congenital disorders of glycosylation (CDG) are defects in glycoprotein and glycolipid glycan synthesis and attachment. They affect multiple organ/systems, but non-specific symptoms render the diagnosis of the different CDG very challenging. Phosphomannomutase 2 (PMM2)-CDG is the most common CDG, but advances in genetic analysis have shown others to occur more commonly than previously thought. The present work reports the clinical and mutational spectrum of 25 non-PMM2 CDG patients. The most common clinical symptoms were hypotonia (80%), motor or psychomotor disability (80%) and craniofacial dysmorphism (76%). Based on their serum transferrin isoform profile, 18 were classified as CDG-I and 7 as CDG-II. Pathogenic variations were found in 16 genes (ALG1, ALG6, ATP6V0A2, B4GALT1, CCDC115, COG7, DOLK, DPAGT1, DPM1, GFPT1, MPI, PGM1, RFT1, SLC35A2, SRD5A3, and SSR4). Overall, 27 variants were identified, 12 of which are novel. The results highlight the importance of combining genetic and biochemical analyses for the early diagnosis of this heterogeneous group of disorders.

The impact of alpha-1 antitrypsin deficiency alleles on lung cancer survival.

Different studies have shown that carrying an alpha-1 antitrypsin (AAT) deficiency allele is an independent risk factor for developing lung cancer (LC). However, to date, little is known regarding whether carrying a deficiency allele may be a prognostic factor in the evolution of LC. A prospective observational study was carried out which consecutively included patients diagnosed with LC in University Hospital "Nuestra Señora de Candelaria" between December 2017 and August 2020. A blood sample was taken from each of the patients in order to determine both AAT serum concentration and genotype. Based on AAT genotype, patients were divided into the deficiency (Pi*≠MM) or non-deficiency (Pi*=MM) group. One hundred and sixty-four patients were included. The average length of follow-up was 13±10 months. Patients were classified as stage I (4.2%), stage II (8.3%), stage III (31.2%) and stage IV (56.3%), according to tumour, node and metastasis (TNM) staging. Twenty-eight patients (17%) were carriers of a deficiency allele (6 Pi*MS, 1 Pi*MZ, 1 Pi*MMheerlen). No significant differences were found with respect to baseline characteristics between Pi*≠MM and Pi*=MM. Patients in the Pi*≠MM group had a higher risk of death in the first 6 months after the LC diagnosis compared to Pi*=MM subjects (HR =2.04; 95% CI: 1.04-4.0; P=0.038). The presence of an AAT deficiency genotype could be a potential prognostic marker in LC. However, larger studies that justify these findings are needed.