Magic™ Anti-Hemoglobin monoclonal antibody, clone N9232642

Background: Chromosomal microarray analysis (CMA) is recommended as the first-tier clinical diagnostic test for individuals with developmental disabilities. In addition to detecting copy number variations, CMA platforms with single nucleotide polymorphism probes can detect large homozygous regions within the genome, which represent potential risk for recessively inherited disorders. Methods: To determine the frequency in which pathogenic or likely pathogenic variants can be detected in these regions of homozygosity, we performed whole exome sequencing (WES) in 53 individuals where homozygosity was detected by CMA. These patients were referred to our clinical laboratory for a variety of neurodevelopmental conditions including autism spectrum disorder, developmental delay, epilepsy, intellectual disability and microcephaly. Results: In 11.3% (6/53) of cases, the analysis of homozygous variants revealed pathogenic or likely pathogenic variants in GJB2, TPP1, SLC25A15, TYR, PCCB, and NDUFV2 which are implicated in a variety of diseases. The evaluation of heterozygous variants with autosomal dominant inheritance, compound heterozygotes and variants with X-linked inheritance revealed pathogenic or likely pathogenic variants in PNPLA4, CADM1, HBB, SOS1, SFTPC, OTC and ASMT in 15.1% (8/53) of cases. Two of these patients harbored both homozygous and heterozygous variants relevant to their phenotypes (TPP1 and OTC; GJB2 and ASMT). Conclusions: Our study highlights the clinical utility of WES in individuals whose CMA uncovers homozygosity. Importantly, we show that when the phenotype is complex and homozygosity levels are high, WES can identify a significant number of relevant variants that explain neurodevelopmental phenotypes, and these mutations may lie outside of the regions of homozygosity, suggesting that the appropriate follow up test is WES rather than targeted sequencing.

This paper aims to investigate the feasibility of performing pre-implantation genetic diagnosis (PGD) and pre-implantation genetic screening (PGS) simultaneously by a universal strategy without the requirement of genotyping relevant affected family members or lengthy preliminary work on linkage analysis. By utilizing a universal Mutated Allele Revealed by Sequencing with Aneuploidy and Linkage Analyses (MARSALA) strategy based on low depth whole genome sequencing (similar to 3x), not involving specific primers' design nor the enrichment of SNP markers for haplotype construction. Single-sperm cells and trephectoderm cells from in vitro fertilized embryos from a couple carrying HBB mutations were genotyped. Haplotypes of paternal alleles were constructed and investigated in embryos, and the chromosome copy number profiles were simultaneously analyzed. The universal MARSALA strategy allows the selection of a euploid embryo free of disease mutations for in uterus transfer and successful pregnancy. A follow-up amniocentesis was performed at 17 weeks of gestation to confirm the PGD/PGS results. We present the first successful PGD procedure based on genotyping multiple single-sperm cells to obtain SNP linkage information. Our improved PGD/PGS procedure does not require genotyping the proband or relevant family members and therefore can be applicable to a wider population of patients when conducting PGD for monogenic disorders.