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Variable clinical phenotypes in a family with homozygous c.1159G>A mutation in the thyroid peroxidase gene

Lee CC, Harun F, Jalaludin MY, Heh CH, Othman R, Kang IN, et al.

Horm Res Paediatr, 2014;81(5):356-60.
PMID: 24717978 DOI: 10.1159/000359922

Defects in the thyroid peroxidase (TPO) gene have been associated with goitrous congenital hypothyroidism (CH).

Matched MeSH terms: RNA Splicing/genetics
DEPDC5 mutations in familial and sporadic focal epilepsy

Tsai MH, Chan CK, Chang YC, Yu YT, Chuang ST, Fan WL, et al.

Clin Genet, 2017 Oct;92(4):397-404.
PMID: 28170089 DOI: 10.1111/cge.12992

BACKGROUND AND AIMS: Mutations in the disheveled, Egl-10 and pleckstrin domain-containing protein 5 (DEPDC5) gene have emerged as an important cause of various familial focal epilepsy syndromes. However, the significance of DEPDC5 mutations in patients with sporadic focal epilepsy has yet to be characterized.
MATERIALS AND METHODS: We studied a kindred of familial focal epilepsy with variable foci using whole-exome sequencing. We subsequently studied a cohort of 293 patients with focal epilepsy and sequenced all exons of DEPDC5 using targeted resequencing.
RESULTS: We reported a Taiwanese family with a novel splice site mutation which affected mRNA splicing and activated the downstream mammalian target of rapamycin (mTOR) pathway. Among patients with focal epilepsies, the majority (220/293) of these patients had sporadic focal epilepsy without malformation of cortical development. Two (0.9%) of these patients had probably pathogenic mutations in the DEPDC5 gene.
DISCUSSION AND CONCLUSIONS: Our finding suggests that DEPDC5 is not only the most common gene for familial focal epilepsy but also could be a significant gene for sporadic focal epilepsy. Since focal epilepsies account for more than 60% of all epilepsies, the effect of mTORC1 inhibitor on patients with focal epilepsy due to DEPDC5 mutations will be an important future direction of research.

Matched MeSH terms: RNA Splicing/genetics
A case of beta-thalassemia with a C----T substitution at position 654 of the second intervening sequence of the beta-globin gene

Jo T, Momita S, Sadamori N, Tomonaga M, Fucharoem S, Fukumaki Y, et al.

Intern. Med., 1992 Feb;31(2):269-72.
PMID: 1600278

A 26-year-old Chinese-Malaysian female patient with beta-thalassemia is presented. The main hematological values found in this patient were as follows: 1) normocytic hypochromic anemia (RBC 444 x 10(4)/microliters, Hb 11.8 g/dl) with marked anisopoikilocytosis, 2) erythroid hyperplasia, and 3) increased HbF (HbA 41.4%, HbA2 2.9%, HbF 48.9%). DNA obtained from peripheral leukocytes was analyzed using dot blot hybridization of the polymerase chain reaction (PCR)-amplified DNA with allele-specific oligonucleotide probes. A C----T substitution at position 654 of the second intervening sequence (IVS-2) was detected in her beta-globin clone.

Matched MeSH terms: RNA Splicing/genetics
Novel MDM2 splice variants identified from oral squamous cell carcinoma

Sam KK, Gan CP, Yee PS, Chong CE, Lim KP, Karen-Ng LP, et al.

Oral Oncol, 2012 Nov;48(11):1128-35.
PMID: 22705356 DOI: 10.1016/j.oraloncology.2012.05.016

The presence of a variety of MDM2 splice variants has been reported in a range of different tumor types and is associated with poor patient prognosis. Furthermore, several MDM2 variants have been shown to have oncogenic properties. Despite this, MDM2 splice variants have not been comprehensively characterized in oral squamous cell carcinoma (OSCC).

Matched MeSH terms: RNA Splicing/genetics*
Fulltext The BRCA2 c.68-7T > A variant is not pathogenic: A model for clinical calibration of spliceogenicity

Colombo M, Lòpez-Perolio I, Meeks HD, Caleca L, Parsons MT, Li H, et al.

Hum Mutat, 2018 May;39(5):729-741.
PMID: 29460995 DOI: 10.1002/humu.23411

Although the spliceogenic nature of the BRCA2 c.68-7T > A variant has been demonstrated, its association with cancer risk remains controversial. In this study, we accurately quantified by real-time PCR and digital PCR (dPCR), the BRCA2 isoforms retaining or missing exon 3. In addition, the combined odds ratio for causality of the variant was estimated using genetic and clinical data, and its associated cancer risk was estimated by case-control analysis in 83,636 individuals. Co-occurrence in trans with pathogenic BRCA2 variants was assessed in 5,382 families. Exon 3 exclusion rate was 4.5-fold higher in variant carriers (13%) than controls (3%), indicating an exclusion rate for the c.68-7T > A allele of approximately 20%. The posterior probability of pathogenicity was 7.44 × 10-115 . There was neither evidence for increased risk of breast cancer (OR 1.03; 95% CI 0.86-1.24) nor for a deleterious effect of the variant when co-occurring with pathogenic variants. Our data provide for the first time robust evidence of the nonpathogenicity of the BRCA2 c.68-7T > A. Genetic and quantitative transcript analyses together inform the threshold for the ratio between functional and altered BRCA2 isoforms compatible with normal cell function. These findings might be exploited to assess the relevance for cancer risk of other BRCA2 spliceogenic variants.

Matched MeSH terms: RNA Splicing/genetics*
Fulltext Doubly Spliced RNA of Hepatitis B Virus Suppresses Viral Transcription via TATA-Binding Protein and Induces Stress Granule Assembly

Tsai KN, Chong CL, Chou YC, Huang CC, Wang YL, Wang SW, et al.

J Virol, 2015 Nov;89(22):11406-19.
PMID: 26339052 DOI: 10.1128/JVI.00949-15

The risk of liver cancer in patients infected with the hepatitis B virus (HBV) and their clinical response to interferon alpha therapy vary based on the HBV genotype. The mechanisms underlying these differences in HBV pathogenesis remain unclear. In HepG2 cells transfected with a mutant HBV(G2335A) expression plasmid that does not transcribe the 2.2-kb doubly spliced RNA (2.2DS-RNA) expressed by wild-type HBV genotype A, the level of HBV pregenomic RNA (pgRNA) was higher than that in cells transfected with an HBV genotype A expression plasmid. By using cotransfection with HBV genotype D and 2.2DS-RNA expression plasmids, we found that a reduction of pgRNA was observed in the cells even in the presence of small amounts of the 2.2DS-RNA plasmid. Moreover, ectopic expression of 2.2DS-RNA in the HBV-producing cell line 1.3ES2 reduced the expression of pgRNA. Further analysis showed that exogenously transcribed 2.2DS-RNA inhibited a reconstituted transcription in vitro. In Huh7 cells ectopically expressing 2.2DS-RNA, RNA immunoprecipitation revealed that 2.2DS-RNA interacted with the TATA-binding protein (TBP) and that nucleotides 432 to 832 of 2.2DS-RNA were required for efficient TBP binding. Immunofluorescence experiments showed that 2.2DS-RNA colocalized with cytoplasmic TBP and the stress granule components, G3BP and poly(A)-binding protein 1 (PABP1), in Huh7 cells. In conclusion, our study reveals that 2.2DS-RNA acts as a repressor of HBV transcription through an interaction with TBP that induces stress granule formation. The expression of 2.2DS-RNA may be one of the viral factors involved in viral replication, which may underlie differences in clinical outcomes of liver disease and responses to interferon alpha therapy between patients infected with different HBV genotypes.

Matched MeSH terms: RNA Splicing/genetics