The molecular complexity of COL2A1 splicing variants and their significance in phenotype severity.

Pathogenic single nucleotide variants (SNVs) found in the COL2A1 gene are associated with a broad range of skeletal dysplasias due to their impact on the structure and function of the Col2a1 protein. However, the molecular mechanisms of some nucleotide variants detected during diagnostic testing remain unclear. The interpretation of missense and splicing variants caused by SNVs poses a significant challenge for clinicians. In this work, we analyzed 22 splicing variants in the COL2A1 gene which have been found in patients with COL2A1-associated skeletal dysplasias. Using a minigene system, we investigated the impact of these SNVs on splicing and gained insights into their molecular mechanisms and genotype-phenotype correlations for each patient. The results of our study are very useful for improving the accuracy of diagnosis and the management of patients with skeletal dysplasias caused by SNVs in the COL2A1 gene.

Novel intronic variant in PALB2 gene and effective prevention of Fanconi anemia in family.

Despite the acceptance of NextGen sequencing as a diagnostic modality suitable for probands and carriers of Mendelian diseases, its efficiency in identifying causal mutations is limited by both technical aspects of variant call algorithms and by imperfect, consensus-based criteria for assessing the pathogenicity of the findings. Here we describe the medical history of the family with a child born with Fanconi anemia. In this case, typical diagnostic routines were complicated by unusual combination of mutations. PALB2 variant NM_024675.3:c.172_175delTTGT (p.Gln60Argfs) in maternal sample, previously classified as a definitely pathogenic frameshift mutation, was in compound heterozygous state with PALB2 NM_024675.3:c.3114-16_3114-11del (p.Asn1039Glyfs*7), which led to validated PALB2 exon 11 skipping event in paternal locus. Findings enabled the development of the PGТ and successful selection of two mutation-free embryos. We show that even in absence of definitive exome findings, clinician-guided research inquiries into the structure and function of the suspected loci allow definitive diagnosis. Described case provides an example of a crucial input of an investigational workflow in genetic prognosis and successful PGT.