scholarly journals Low‐level germline mosaicism of a novel SMARCA2 missense variant: Expanding the phenotypic spectrum and mode of genetic transmission

2021 ◽  
Author(s):  
Nina Pan ◽  
Songchang Chen ◽  
Xiaoqiang Cai ◽  
Jianli Li ◽  
Tao Yu ◽  
...  
Keyword(s):  
Missense Variant ◽  
Germline Mosaicism ◽  
Genetic Transmission ◽  
Low Level ◽  
Phenotypic Spectrum

scholarly journals Allelic Variants in Established Hypopituitarism Genes Expand Our Knowledge of the Phenotypic Spectrum

Genes ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 1128
Author(s):  
Marilena Nakaguma ◽  
Nathalia Garcia Bianchi Pereira Ferreira ◽  
Anna Flavia Figueredo Benedetti ◽  
Mariana Cotarelli Madi ◽  
Juliana Moreira Silva ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Male Patient ◽  
Missense Variant ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Incomplete Penetrance ◽  
Growth Hormone Gene ◽  
Posterior Lobe ◽  
Allelic Variants ◽  
Phenotypic Spectrum

We report four allelic variants (three novel) in three genes previously established as causal for hypopituitarism or related disorders. A novel homozygous variant in the growth hormone gene, GH1 c.171delT (p.Phe 57Leufs*43), was found in a male patient with severe isolated growth hormone deficiency (IGHD) born to consanguineous parents. A hemizygous SOX3 allelic variant (p.Met304Ile) was found in a male patient with IGHD and hypoplastic anterior pituitary. YASARA, a tool to evaluate protein stability, suggests that p.Met304Ile destabilizes the SOX3 protein (ΔΔG = 2.49 kcal/mol). A rare, heterozygous missense variant in the TALE homeobox protein gene, TGIF1 (c.268C>T:p.Arg90Cys) was found in a patient with combined pituitary hormone deficiency (CPHD), diabetes insipidus, and syndromic features of holoprosencephaly (HPE). This variant was previously reported in a patient with severe holoprosencephaly and shown to affect TGIF1 function. A novel heterozygous TGIF1 variant (c.82T>C:p.Ser28Pro) was identified in a patient with CPHD, pituitary aplasia and ectopic posterior lobe. Both TGIF1 variants have an autosomal dominant pattern of inheritance with incomplete penetrance. In conclusion, we have found allelic variants in three genes in hypopituitarism patients. We discuss these variants and associated patient phenotypes in relation to previously reported variants in these genes, expanding our knowledge of the phenotypic spectrum in patient populations.

TBL1XR1 associated intellectual disability, a new missense variant with dysmorphic features plus autism: Expanding the phenotypic spectrum

2021 ◽  
Author(s):  
Ignacio Arroyo Carrera ◽  
Miguel Fernández‐Burriel ◽  
Pablo Lapunzina ◽  
Jair Antonio Tenorio ◽  
Verónica Deyanira García Navas ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Missense Variant ◽  
Dysmorphic Features ◽  
Phenotypic Spectrum

scholarly journals Alpers- and MNGIE-like disease with disturbed CSF folate transport and an unusual mode of genetic transmission of POLG mutations: a case report

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Rudolf Korinthenberg ◽  
Janbernd Kirschner ◽  
Matthias Eckenweiler ◽  
Robert Steinfeld ◽  
Nana Nino Tatishvili ◽  
...  
Keyword(s):  
Folate Receptor ◽  
Systemic Disease ◽  
Epileptic Seizures ◽  
The Other ◽  
Buccal Swab ◽  
Compound Heterozygous ◽  
Folate Transport ◽  
Lethal Outcome ◽  
Germline Mosaicism ◽  
Genetic Transmission

We report about a family with three of five siblings affected by a variable remitting-relapsing disease with epileptic seizures, coma and abdominal crises, and lethal outcome in all. In the youngest son and in one of his deceased brothers we identified two disease causing compound heterozygous POLG mutations. One of these was inherited from the mother, but the other was absent in the father`s blood, saliva, buccal swab and hair bulbs although his paternity was proven genetically. Thus, we assume germline mosaicism for this mutation in the father. Very low 5-methyltetrahydrofolate (5-MTHF) and absence of folate receptor-alpha was repeatedly found in the CSF of the youngest brother indicating a secondary cerebral folate transport deficiency. Folinic acid supplementation over 18 months resulted in some improvement of the neurological condition; however, it did not prevent progression of the systemic disease.

scholarly journals Case Report: Low-Level Maternal Mosaicism of a Novel CREBBP Variant Causes Recurrent Rubinstein-Taybi Syndrome in Two Siblings of a Chinese Family

2021 ◽  
Vol 12 ◽  
Author(s):  
Shaobin Lin ◽  
Zhiming He ◽  
Linhuan Huang ◽  
Jialiu Liu ◽  
Ting Lei ◽  
...  
Keyword(s):  
Peripheral Blood ◽  
De Novo ◽  
Recurrence Risk ◽  
Chinese Family ◽  
Sequencing Analysis ◽  
Mrna Levels ◽  
Germline Mosaicism ◽  
Low Level ◽  
Normal Individuals ◽  
High Depth

Familial Rubinstein-Taybi syndrome (RSTS) with recurrent RSTS siblings and apparently unaffected parents is rare; such cases might result from parental somatic and/or germline mosaicism. Parental low-level (<10%) germline mosaicism in the CREBBP-associated RSTS family has not been reported. Here, we present our studies of a Chinese family with two RSTS siblings and apparently unaffected parents. We detected the apparent de novo variant (DNV) c.3235C>T (p.Gln1079*) in CREBBP in the siblings via trio whole-exome sequencing. High-depth next-generation sequencing (NGS) for the parents revealed a low-level (<10%) mosaic variant in both the peripheral blood (3.64%) and buccal mucosa (1.94%) of the unaffected mother, indicating maternal somatic and germline mosaicism. Peripheral blood RNA-sequencing analysis for the patients and normal individuals indicated that the c.3235C>T (p.Gln1079*) non-sense variant did not trigger nonsense-mediated mRNA decay to reduce CREBBP mRNA levels. Transcriptome analysis revealed 151 downregulated mRNAs and 132 upregulated mRNAs between the patients and normal individuals. This study emphasizes that high-depth NGS using multiple specimens might be applied for a family with an affected sibling caused by an apparent CREBBP DNV to identify potential low-level parental mosaicism and provide an assessment of recurrence risk.

scholarly journals Germline mosaicism of a missense variant in KCNC2 in a multiplex family with autism and epilepsy

2021 ◽  
Author(s):  
Elvisa Mehinovic ◽  
Teddi Gray ◽  
Meghan Campbell ◽  
Jenny Ekholm ◽  
Aaron Wenger ◽  
...  
Keyword(s):  
De Novo ◽  
Copy Number Variants ◽  
Missense Variant ◽  
Missense Mutations ◽  
Sequencing Data ◽  
Multiplex Family ◽  
Protein Coding ◽  
Germline Mosaicism ◽  
Current Decay ◽  
Long Read

ABSTRACTCurrently, protein-coding de novo variants and large copy number variants have been identified as important for ∼30% of individuals with autism. One approach to identify relevant variation in individuals who lack these types of events is by utilizing newer genomic technologies. In this study, highly accurate PacBio HiFi long-read sequencing was applied to a family with autism, treatment-refractory epilepsy, cognitive impairment, and mild dysmorphic features (two affected female full siblings, parents, and one unaffected sibling) with no known clinical variant. From our long-read sequencing data, a de novo missense variant in the KCNC2 gene (encodes Kv3.2 protein) was identified in both affected children. This variant was phased to the paternal chromosome of origin and is likely a germline mosaic. In silico assessment of the variant revealed it was in the top 0.05% of all conserved bases in the genome, and was predicted damaging by Polyphen2, MutationTaster, and SIFT. It was not present in any controls from public genome databases nor in a joint-call set we generated across 49 individuals with publicly available PacBio HiFi data. This specific missense mutation (Val473Ala) has been shown in both an ortholog and paralog of Kv3.2 to accelerate current decay, shift the voltage dependence of activation, and prevent the channel from entering a long-lasting open state. Seven additional missense mutations have been identified in other individuals with neurodevelopmental disorders (p = 1.03 × 10−5). KCNC2 is most highly expressed in the brain; in particular, in the thalamus and is enriched in GABAergic neurons. Long-read sequencing was useful in discovering the relevant variant in this family with autism that had remained a mystery for several years and will potentially have great benefits in the clinic once it is widely available.

Detection of low-level somatic and germline mosaicism by denaturing high-performance liquid chromatography in a EURO-MRX family with SLC6A8 deficiency

Neurogenetics ◽  
2008 ◽  
Vol 9 (3) ◽  
pp. 183-190 ◽  
Author(s):  
Ofir T. Betsalel ◽  
Jiddeke M. van de Kamp ◽  
Cristina Martínez-Muñoz ◽  
Efraim H. Rosenberg ◽  
Arjan P. M. de Brouwer ◽  
...  
Keyword(s):  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Germline Mosaicism ◽  
Low Level

scholarly journals Case Report: Identification of Maternal Low-Level Mosaicism in the Dystrophin Gene by Droplet Digital Polymerase Chain Reaction

2021 ◽  
Vol 12 ◽  
Author(s):  
Pengzhen Jin ◽  
Xiaoyang Gao ◽  
Miaomiao Wang ◽  
Yeqing Qian ◽  
Jingjin Yang ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Peripheral Blood ◽  
De Novo ◽  
Dystrophin Gene ◽  
Chain Reaction ◽  
Germline Mosaicism ◽  
Blood Samples ◽  
Low Level ◽  
Polymerase Chain ◽  
Digital Polymerase Chain Reaction

Germline mosaicism should be suspected when the same de novo mutations are identified in a second pregnancy with asymptomatic parents. Our study aims to find a feasible approach to reveal the existence of germline mosaicism. Multiplex Ligation-dependent Probe Amplification was performed on a Duchenne muscular dystrophy affected pedigree to detect deletion mutations. Then gap-polymerase chain reaction was performed to amplify the breakpoints junction sequence. Droplet digital polymerase chain reaction was utilized to identify the mutation frequencies in healthy parents. The same deletion in the exon 51 of the dystrophin gene, which was 50,035 bp in size, was detected in the proband and the fetus but not in their parents. Droplet digital polymerase chain reaction analysis of peripheral blood samples revealed mutant alleles of 3.53% in maternal blood cells. We here report a case of maternal low-level mosaicism confirmed by droplet digital polymerase chain reaction in peripheral blood samples, which reveals the existence of germline mosaicism. Gap-polymerase chain reaction combined with droplet digital polymerase chain reaction provide insights into the detection of germline mosaicism.

scholarly journals Allelic Variants in Established Hypopituitarism Genes Expands Our Knowledge of Phenotypic Spectrum

2021 ◽  
Author(s):  
Marilena Nakaguma ◽  
Nathalia Garcia Bianchi Pereira Ferreira ◽  
Anna Flavia Figueredo Benedetti ◽  
Mariana Cotarelli Madi ◽  
Juliana Moreira Silva ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Male Patient ◽  
Missense Variant ◽  
Hormone Deficiency ◽  
Pituitary Hormone ◽  
Incomplete Penetrance ◽  
Growth Hormone Gene ◽  
Posterior Lobe ◽  
Allelic Variants ◽  
Phenotypic Spectrum

We report four allelic variants (3 novel) in three genes previously established as causal for hypopituitarism or related disorders. A novel homozygous variant in the growth hormone gene, GH1 c.171delT (p. Phe 57Leufs * 43), was found in a male patient with severe isolated growth hormone deficiency (IGHD) born to consanguineous parents. A SOX3 allelic variant (p.Met304Ile) was found in a male patient with IGHD and hypoplastic anterior pituitary. YASARA, a tool to evaluate protein stability, suggests that p.Met304Ile destabilizes the SOX3 protein (ΔΔG = 2.49 kcal/mol). A rare, heterozygous missense variant in the TALE homeobox protein gene, TGIF1 (c.268C>T:p.Arg90Cys) was found in a patient with combined pituitary hormone deficiency (CPHD), diabetes insipidus, and syndromic features of holoprosencephaly (HPE). A novel heterozygous TGIF1 variant (c.82T>C:p.Ser28Pro) was identified in a patient with CPHD, pituitary aplasia and ectopic posterior lobe. Both TGIF1 variants have an autosomal dominant pattern of inheritance with incomplete penetrance. In conclusion, we have found allelic variants in 3 genes in hypopituitarism patients. We discuss these variants and associated patient phenotypes in relation to previously reported variants in these genes, expanding our knowledge of the phenotypic spectrum in patient populations.

scholarly journals Further phenotypic delineation of the auriculocondylar syndrome type 2 with literature review

2020 ◽  
Author(s):  
Ewelina Bukowska-Olech ◽  
Anna Sowińska-Seidler ◽  
Filip Łojek ◽  
Delfina Popiel ◽  
Joanna Walczak-Sztulpa ◽  
...  
Keyword(s):  
Somatic Mosaicism ◽  
Missense Variant ◽  
Pharyngeal Arches ◽  
Developmental Defects ◽  
Targeted Next Generation Sequencing ◽  
Phenotypic Spectrum ◽  
Whole Exome ◽  
Low Coverage ◽  
Generation Sequencing

AbstractAuriculocondylar syndrome (ACS) is an ultra-rare disorder that arises from developmental defects of the first and second pharyngeal arches. Three subtypes of ACS have been described so far, i.e., ACS1 (MIM: 602483), ACS2 (MIM: 600810), and ACS3 (MIM: 131240). The majority of patients, however, are affected by ACS2, which results from the mutations in the PLCB4 gene. Herein, we have described an 8-year-old male patient presenting with ACS2 and summarized the molecular and phenotypic spectrum of the syndrome. We have also compared the clinical features of our case to three other previously described cases (one sporadic and two familial) harboring the same heterozygous missense variant c.1862G>A, p.Arg621His in the PLCB4 gene. The mutation was detected using whole-exome sequencing (WES). Due to low coverage of WES and suspicion of somatic mosaicism, the variant was additionally reassessed by deep targeted next-generation sequencing panel of genes related to the craniofacial disorders, and next confirmed by Sanger sequencing. ACS2 presents high intra- and interfamilial phenotypic heterogeneity that impedes reaching an exact clinical and molecular diagnosis. Thus, describing additional cases, carrying even the known mutation, but resulting in variable phenotypes, is essential for better understanding of such orphan Mendelian diseases.

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