Supplementary Material for: Cytosine Methylation of an Ancient Satellite Family in the Wild Beet Beta procumbens

DNA methylation is an essential epigenetic feature for the regulation and maintenance of heterochromatin. Satellite DNA is a repetitive sequence component that often occurs in large arrays in heterochromatin of subtelomeric, intercalary and centromeric regions. Knowledge about the methylation status of satellite DNA is important for understanding the role of repetitive DNA in heterochromatization. In this study, we investigated the cytosine methylation of the ancient satellite family pEV in the wild beet <i>Beta procumbens</i>. The pEV satellite is widespread in species-specific pEV subfamilies in the genus <i>Beta</i> and most likely originated before the radiation of the Betoideae and Chenopodioideae. In <i>B. procumbens</i>, the pEV subfamily occurs abundantly and spans intercalary and centromeric regions. To uncover its cytosine methylation, we performed chromosome-wide immunostaining and bisulfite sequencing of pEV satellite repeats. We found that CG and CHG sites are highly methylated while CHH sites show only low levels of methylation. As a consequence of the low frequency of CG and CHG sites and the preferential occurrence of most cytosines in the CHH motif in pEV monomers, this satellite family displays only low levels of total cytosine methylation

RLIM Is a candidate dosage-sensitive gene for individuals with varying duplications of Xq13, intellectual disability, and distinct facial features

Interpretation of the significance of maternally inherited X chromosome variants in males with neurocognitive phenotypes continues to present a challenge to clinical geneticists and diagnostic laboratories. Here we report 14 males from 9 families with duplications at the Xq13.2-q13.3 locus with a common facial phenotype, intellectual disability (ID), distinctive behavioral features, and a seizure disorder in two cases. All tested carrier mothers had normal intelligence. The duplication arose de novo in three mothers where grandparental testing was possible. In one family the duplication segregated with ID across three generations. RLIM is the only gene common to our duplications. However, flanking genes duplicated in some but not all the affected individuals included the brain-expressed genes NEXMIF, SLC16A2, and the long non-coding RNA gene FTX. The contribution of the RLIM-flanking genes to the phenotypes of individuals with different size duplications has not been fully resolved. Missense variants in RLIM have recently been identified to cause X-linked ID in males, with heterozygous females typically having normal intelligence and highly skewed X chromosome inactivation. We detected consistent and significant increase of RLIM mRNA and protein levels in cells derived from seven affected males from five families with the duplication. Subsequent analysis of MDM2, one of the targets of the RLIM E3 ligase activity, showed consistent downregulation in cells from the affected males. All the carrier mothers displayed normal RLIM mRNA levels and had highly skewed X chromosome inactivation. We propose that duplications at Xq13.2-13.3 including RLIM cause a recognizable but mild neurocognitive phenotype in hemizygous males.Elizabeth E. Palmer, Renee Carroll, Marie Shaw, Raman Kumar, Andre E. Minoche, Melanie Leffler, Lucinda Murray, Rebecca Macintosh, Dale Wright, Chris Troedson, Fiona McKenzie, Sharron Townshend, Michelle Ward, Urwah Nawaz, Anja Ravine, Cassandra K. Runke, Erik C. Thorland, Marybeth Hummel, Nicola Foulds, Olivier Pichon, Bertrand Isidor, Cédric Le Caignec, Bénédicte Demeer, Joris Andrieux, Salam Hadah Albarazi, Ann Bye, Rani Sachdev, Edwin P. Kirk, Mark J. Cowley, Mike Field, and Jozef Gec

Diagnostic yield of whole genome sequencing after non-diagnostic exome sequencing or gene panel in developmental and epileptic encephalopathies

First published February 10, 2021OBJECTIVE: To assess the benefits and limitations of whole genome sequencing (WGS) compared to exome sequencing (ES) or multigene panel (MGP) in the molecular diagnosis of developmental and epileptic encephalopathies (DEE). METHODS: We performed WGS of 30 comprehensively phenotyped DEE patient trios that were undiagnosed after first-tier testing, including chromosomal microarray (CMA), and either research ES (n=15) or diagnostic MGP (n=15). RESULTS: 8 diagnoses were made in the 15 individuals who received prior ES (53%): 3 individuals had complex structural variants; 5 had ES-detectable variants which now had additional evidence for pathogenicity. 11 diagnoses were made in the 15 MGP-negative individuals (68%); the majority (n=10) involved genes not included in the panel, particularly in individuals with post-neonatal onset of seizures and those with more complex presentations including movement disorders, dysmorphic features and/or multi-organ involvement. 42% of diagnoses were autosomal recessive or X-chromosome linked. CONCLUSION: WGS was able to improve diagnostic yield over ES primarily through the detection of complex structural variants (n=3). The higher diagnostic yield was otherwise better attributed to the power of re-analysis rather than inherent advantages of the WGS platform. Additional research is required to assist in the assessment of pathogenicity of novel non-coding and complex structural variants and further improve diagnostic yield for patients with DEE and other neurogenetic disorders.Elizabeth Emma Palmer, Rani Sachdev, Rebecca Macintosh, Uirá Souto Melo, Stefan Mundlos, Sarah Righetti ... et al

Fatal Perinatal Mitochondrial Cardiac Failure Caused by Recurrent De Novo Duplications in the ATAD3 Locus

Background: In about half of all patients with a suspected monogenic disease, genomic investigations fail to identify the diagnosis. A contributing factor is the difficulty with repetitive regions of the genome, such as those generated by segmental duplications. The ATAD3 locus is one such region, in which recessive deletions and dominant duplications have recently been reported to cause lethal perinatal mitochondrial diseases characterized by pontocerebellar hypoplasia or cardiomyopathy, respectively. Methods: Whole exome, whole genome and long-read DNA sequencing techniques combined with studies of RNA and quantitative proteomics were used to investigate 17 subjects from 16 unrelated families with suspected mitochondrial disease. Findings: We report six different de novo duplications in the ATAD3 gene locus causing a distinctive presentation including lethal perinatal cardiomyopathy, persistent hyperlactacidemia, and frequently corneal clouding or cataracts and encephalopathy. The recurrent 68 Kb ATAD3 duplications are identifiable from genome and exome sequencing but usually missed by microarrays. The ATAD3 duplications result in the formation of identical chimeric ATAD3A/ATAD3C proteins, altered ATAD3 complexes and a striking reduction in mitochondrial oxidative phosphorylation complex I and its activity in heart tissue. Conclusions: ATAD3 duplications appear to act in a dominant-negative manner and the de novo inheritance infers a low recurrence risk for families, unlike most pediatric mitochondrial diseases. More than 350 genes underlie mitochondrial diseases. In our experience the ATAD3 locus is now one of the five most common causes of nuclear-encoded pediatric mitochondrial disease but the repetitive nature of the locus means ATAD3 diagnoses may be frequently missed by current genomic strategies. Funding: Australian NHMRC, US Department of Defense, Japanese AMED and JSPS agencies, Australian Genomics Health Alliance and Australian Mito Foundation

Architecture and evolution of a minute plant genome

It has been argued that the evolution of plant genome size is principally unidirectional and increasing owing to the varied action of whole-genome duplications (WGDs) and mobile element proliferation1. However, extreme genome size reductions have been reported in the angiosperm family tree. Here we report the sequence of the 82-megabase genome of the carnivorous bladderwort plant Utricularia gibba. Despite its tiny size, the U. gibba genome accommodates a typical number of genes for a plant, with the main difference from other plant genomes arising from a drastic reduction in non-genic DNA. Unexpectedly, we identified at least three rounds of WGD in U. gibba since common ancestry with tomato (Solanum) and grape (Vitis). The compressed architecture of the U. gibba genome indicates that a small fraction of intergenic DNA, with few or no active retrotransposons, is sufficient to regulate and integrate all the processes required for the development and reproduction of a complex organism