@article {138, title = {Complex mosaic structural variations in human fetal brains.}, journal = {Genome Res}, volume = {30}, year = {2020}, month = {2020 12}, pages = {1695-1704}, abstract = {

Somatic mosaicism, manifesting as single nucleotide variants (SNVs), mobile element insertions, and structural changes in the DNA, is a common phenomenon in human brain cells, with potential functional consequences. Using a clonal approach, we previously detected 200-400 mosaic SNVs per cell in three human fetal brains (15-21 wk postconception). However, structural variation in the human fetal brain has not yet been investigated. Here, we discover and validate four mosaic structural variants (SVs) in the same brains and resolve their precise breakpoints. The SVs were of kilobase scale and complex, consisting of deletion(s) and rearranged genomic fragments, which sometimes originated from different chromosomes. Sequences at the breakpoints of these rearrangements had microhomologies, suggesting their origin from replication errors. One SV was found in two clones, and we timed its origin to \~{}14 wk postconception. No large scale mosaic copy number variants (CNVs) were detectable in normal fetal human brains, suggesting that previously reported megabase-scale CNVs in neurons arise at later stages of development. By reanalysis of public single nuclei data from adult brain neurons, we detected an extrachromosomal circular DNA event. Our study reveals the existence of mosaic SVs in the developing human brain, likely arising from cell proliferation during mid-neurogenesis. Although relatively rare compared to SNVs and present in \~{}10\% of neurons, SVs in developing human brain affect a comparable number of bases in the genome (\~{}6200 vs. \~{}4000 bp), implying that they may have similar functional consequences.

}, issn = {1549-5469}, doi = {10.1101/gr.262667.120}, author = {Sekar, Shobana and Tomasini, Livia and Proukakis, Christos and Bae, Taejeong and Manlove, Logan and Jang, Yeongjun and Scuderi, Soraya and Zhou, Bo and Kalyva, Maria and Amiri, Anahita and Mariani, Jessica and Sedlazeck, Fritz J and Urban, Alexander E and Vaccarino, Flora M and Abyzov, Alexej} } @article {56, title = {Evaluation of the detection of GBA missense mutations and other variants using the Oxford Nanopore MinION.}, journal = {Mol Genet Genomic Med}, volume = {7}, year = {2019}, month = {2019 03}, pages = {e564}, abstract = {

BACKGROUND: Mutations in GBA cause Gaucher disease when biallelic and are strong risk factors for Parkinson{\textquoteright}s disease when heterozygous. GBA analysis is complicated by the nearby pseudogene. We aimed to design and validate a method for sequencing GBA using long reads.

METHODS: We sequenced GBA on the Oxford Nanopore MinION as an 8.9~kb amplicon from 102 individuals, including patients with Parkinson{\textquoteright}s and Gaucher diseases. We used NanoOK for quality metrics, NGMLR to align data (after comparing with GraphMap), Nanopolish and Sniffles to call variants, and WhatsHap for phasing.

RESULTS: We detected all known missense mutations in these samples, including the common p.N409S (N370S) and p.L483P (L444P) in multiple samples, and nine rarer ones, as well as a splicing and a truncating mutation, and intronic SNPs. We demonstrated the ability to phase mutations, confirm compound heterozygosity, and assign haplotypes. We also detected two known risk variants in some Parkinson{\textquoteright}s patients. Rare false positives were easily identified and filtered, with the Nanopolish quality score adjusted for the number of reads a very robust discriminator. In two individuals carrying a recombinant allele, we were able to detect and fully define it in one carrier, where it included a 55-base pair deletion, but not in another one, suggesting a limitation of the PCR enrichment method. Missense mutations were detected at the correct zygosity, except for the case where the RecNciI one was missed.

CONCLUSION: The Oxford Nanopore MinION can detect missense mutations and an exonic deletion in this difficult gene, with the added advantages of phasing and intronic analysis. It can be used as an efficient research tool, but additional work is required to exclude all recombinants.

}, issn = {2324-9269}, doi = {10.1002/mgg3.564}, author = {Leija-Salazar, Melissa and Sedlazeck, Fritz J and Toffoli, Marco and Mullin, Stephen and Mokretar, Katya and Athanasopoulou, Maria and Donald, Aimee and Sharma, Reena and Hughes, Derralynn and Schapira, Anthony H V and Proukakis, Christos} }