Haploinsufficiency of PRR12 causes a spectrum of neurodevelopmental, eye, and multisystem abnormalities

Purpose: Proline Rich 12 (PRR12) is a gene of unknown function with suspected DNA-binding activity, expressed in developing mice and human brains. Predicted loss-of-function variants in this gene are extremely rare, indicating high intolerance of haploinsufficiency. Methods: Three individuals with intellectual disability and iris anomalies and truncating de novo PRR12 variants were described previously. We add 21 individuals with similar PRR12 variants identified via matchmaking platforms, bringing the total number to 24. Results: We observed 12 frameshift, 6 nonsense, 1 splice-site, and 2 missense variants and one patient with a gross deletion involving PRR12. Three individuals had additional genetic findings, possibly confounding the phenotype. All patients had developmental impairment. Variable structural eye defects were observed in 12/24 individuals (50%) including anophthalmia, microphthalmia, colobomas, optic nerve and iris abnormalities. Additional common features included hypotonia (61%), heart defects (52%), growth failure (54%), and kidney anomalies (35%). PrediXcan analysis showed that phecodes most strongly associated with reduced predicted PRR12 expression were enriched for eye- (7/30) and kidney- (4/30) phenotypes, such as wet macular degeneration and chronic kidney disease. Conclusion: These findings support PRR12 haploinsufficiency as a cause for a novel disorder with a wide clinical spectrum marked chiefly by neurodevelopmental and eye abnormalities. Graphic Abstract: [Figure not available: see fulltext.

Expanded phenotypic spectrum of neurodevelopmental and neurodegenerative disorder Bryant-Li-Bhoj syndrome with 38 additional individuals

Bryant-Li-Bhoj syndrome (BLBS), which became OMIM-classified in 2022 (OMIM: 619720, 619721), is caused by germline variants in the two genes that encode histone H3.3 (H3-3A/H3F3A and H3-3B/H3F3B) [1-4]. This syndrome is characterized by developmental delay/intellectual disability, craniofacial anomalies, hyper/hypotonia, and abnormal neuroimaging [1, 5]. BLBS was initially categorized as a progressive neurodegenerative syndrome caused by de novo heterozygous variants in either H3-3A or H3-3B [1-4]. Here, we analyze the data of the 58 previously published individuals along 38 unpublished, unrelated individuals. In this larger cohort of 96 people, we identify causative missense, synonymous, and stop-loss variants. We also expand upon the phenotypic characterization by elaborating on the neurodevelopmental component of BLBS. Notably, phenotypic heterogeneity was present even amongst individuals harboring the same variant. To explore the complex phenotypic variation in this expanded cohort, the relationships between syndromic phenotypes with three variables of interest were interrogated: sex, gene containing the causative variant, and variant location in the H3.3 protein. While specific genotype-phenotype correlations have not been conclusively delineated, the results presented here suggest that the location of the variants within the H3.3 protein and the affected gene (H3-3A or H3-3B) contribute more to the severity of distinct phenotypes than sex. Since these variables do not account for all BLBS phenotypic variability, these findings suggest that additional factors may play a role in modifying the phenotypes of affected individuals. Histones are poised at the interface of genetics and epigenetics, highlighting the potential role for gene-environment interactions and the importance of future research

Využitie Real-Time PCR pri kvantitatívnej analýze voľnej fetálnej DNA v krvnom obehu matky

Katedra genetiky a mikrobiologieDepartment of Genetics and MicrobiologyPřírodovědecká fakultaFaculty of Scienc

Analysis of copy number variant (CNV) in genomes of patiens with mental retardation

Mental retardation (MR) is a very heterogeneous common neurodevelopmental disorder with a population prevalence of 2.5-3 %. The importance of genetic factors in the development of MR is high but in a significant number of cases the etiology remains unexplained. Recent studies using array methods pointed to frequent occurrence of copy number variants (CNVs) in patients with MR. Pathogenic CNVs were identified in 10-15 % patients with idiopathic MR and normal karyotype. The aim of our work was the analysis of genome-wide gains and losses of genetic material in a group of Czech patients with MR and a thorough bioinformatic analysis of the genetic changes identified aiming at the assessment of their clinical significance. We performed whole genome analysis using the HumanCytoSNP-12 BeadChips (Illumina) in 183 patients with idiopathic MR, normal karyotype and no FMR1 gene expansion. Data analysis was carried out using two independent programmes, GenomeStudio and QuantiSNP. The findings were subjected to two rounds of thorough bioinformatic analysis. Based on this analysis we classified the CNVs into 4 categories: pathogenic CNVs, probably pathogenic CNVs, CNVs with uncertain clinical significance and benign CNVs. With the exception of the benign variants, all CNVs were confirmed using an independent laboratory..

Expanded phenotypic spectrum of neurodevelopmental and neurodegenerative disorder Bryant-Li-Bhoj syndrome with 38 additional individuals.

Bryant-Li-Bhoj syndrome (BLBS), which became OMIM-classified in 2022 (OMIM: 619720, 619721), is caused by germline variants in the two genes that encode histone H3.3 (H3-3A/H3F3A and H3-3B/H3F3B) [1-4]. This syndrome is characterized by developmental delay/intellectual disability, craniofacial anomalies, hyper/hypotonia, and abnormal neuroimaging [1, 5]. BLBS was initially categorized as a progressive neurodegenerative syndrome caused by de novo heterozygous variants in either H3-3A or H3-3B [1-4]. Here, we analyze the data of the 58 previously published individuals along 38 unpublished, unrelated individuals. In this larger cohort of 96 people, we identify causative missense, synonymous, and stop-loss variants. We also expand upon the phenotypic characterization by elaborating on the neurodevelopmental component of BLBS. Notably, phenotypic heterogeneity was present even amongst individuals harboring the same variant. To explore the complex phenotypic variation in this expanded cohort, the relationships between syndromic phenotypes with three variables of interest were interrogated: sex, gene containing the causative variant, and variant location in the H3.3 protein. While specific genotype-phenotype correlations have not been conclusively delineated, the results presented here suggest that the location of the variants within the H3.3 protein and the affected gene (H3-3A or H3-3B) contribute more to the severity of distinct phenotypes than sex. Since these variables do not account for all BLBS phenotypic variability, these findings suggest that additional factors may play a role in modifying the phenotypes of affected individuals. Histones are poised at the interface of genetics and epigenetics, highlighting the potential role for gene-environment interactions and the importance of future research

De novo SMARCA2 variants clustered outside the helicase domain cause a new recognizable syndrome with intellectual disability and blepharophimosis distinct from Nicolaides–Baraitser syndrome

International audiencePurpose: Nontruncating variants in SMARCA2, encoding a catalytic subunit of SWI/SNF chromatin remodeling complex, cause Nicolaides-Baraitser syndrome (NCBRS), a condition with intellectual disability and multiple congenital anomalies. Other disorders due to SMARCA2 are unknown.Methods: By next-generation sequencing, we identified candidate variants in SMARCA2 in 20 individuals from 18 families with a syndromic neurodevelopmental disorder not consistent with NCBRS. To stratify variant interpretation, we functionally analyzed SMARCA2 variants in yeasts and performed transcriptomic and genome methylation analyses on blood leukocytes.Results: Of 20 individuals, 14 showed a recognizable phenotype with recurrent features including epicanthal folds, blepharophimosis, and downturned nasal tip along with variable degree of intellectual disability (or blepharophimosis intellectual disability syndrome [BIS]). In contrast to most NCBRS variants, all SMARCA2 variants associated with BIS are localized outside the helicase domains. Yeast phenotype assays differentiated NCBRS from non-NCBRS SMARCA2 variants. Transcriptomic and DNA methylation signatures differentiated NCBRS from BIS and those with nonspecific phenotype. In the remaining six individuals with nonspecific dysmorphic features, clinical and molecular data did not permit variant reclassification.Conclusion: We identified a novel recognizable syndrome named BIS associated with clustered de novo SMARCA2 variants outside the helicase domains, phenotypically and molecularly distinct from NCBRS

Dominant variants in the splicing factor PUF60 cause a recognizable syndrome with intellectual disability, heart defects and short stature

International audienceVerheij syndrome, also called 8q24.3 microdeletion syndrome, is a rare condition characterized by ante- and postnatal growth retardation, microcephaly, vertebral anomalies, joint laxity/dislocation, developmental delay (DD), cardiac and renal defects and dysmorphic features. Recently, PUF60 (Poly-U Binding Splicing Factor 60 kDa), which encodes a component of the spliceosome, has been discussed as the best candidate gene for the Verheij syndrome phenotype, regarding the cardiac and short stature phenotype. To date, only one patient has been reported with a de novo variant in PUF60 that probably affects function (c.505C>T leading to p.(His169Tyr)) associated with DD, microcephaly, craniofacial and cardiac defects. Additional patients were required to confirm the pathogenesis of this association and further delineate the clinical spectrum. Here we report five patients with de novo heterozygous variants in PUF60 identified using whole exome sequencing. Variants included a splice-site variant (c.24+1G>C), a frameshift variant (p.(Ile136Thrfs*31)), two nonsense variants (p.(Arg448*) and p.(Lys301*)) and a missense change (p.(Val483Ala)). All six patients with a PUF60 variant (the five patients of the present study and the unique reported patient) have the same core facial gestalt as 8q24.3 microdeletions patients, associated with DD. Other findings include feeding difficulties (3/6), cardiac defects (5/6), short stature (5/6), joint laxity and/or dislocation (5/6), vertebral anomalies (3/6), bilateral microphthalmia and irido-retinal coloboma (1/6), bilateral optic nerve hypoplasia (2/6), renal anomalies (2/6) and branchial arch defects (2/6). These results confirm that PUF60 is a major driver for the developmental, craniofacial, skeletal and cardiac phenotypes associated with the 8q24.3 microdeletion