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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.
The Function of HLA-B*13:01 Involved in the Pathomechanism of Dapsone-Induced Severe Cutaneous Adverse Reactions

Chen WT, Wang CW, Lu CW, Chen CB, Lee HE, Hung SI, et al.

J Invest Dermatol, 2018 07;138(7):1546-1554.
PMID: 29458119 DOI: 10.1016/j.jid.2018.02.004

Dapsone-induced hypersensitivity reactions may cause severe cutaneous adverse reactions, such as drug reaction with eosinophilia and systemic symptoms (DRESS). It has been reported that HLA-B*13:01 is strongly associated with dapsone-induced hypersensitivity reactions among leprosy patients. However, the phenotype specificity and detailed immune mechanism of HLA-B*13:01 remain unclear. We investigated the genetic predisposition, HLA-B*13:01 function, and cytotoxic T cells involved in the pathogenesis of dapsone-induced severe cutaneous adverse reactions. We enrolled patients from Taiwan and Malaysia with DRESS and maculopapular eruption with chronic inflammatory dermatoses. Our results showed that the HLA-B*13:01 allele was present in 85.7% (6/7) of patients with dapsone DRESS (odds ratio = 49.64, 95% confidence interval = 5.89-418.13; corrected P = 2.92 × 10-4) but in only 10.8% (73/677) of general population control individuals in Taiwan. The level of granulysin, the severe cutaneous adverse reaction-specific cytotoxic protein released from cytotoxic T cells, was increased in both the plasma of DRESS patients (36.14 ± 9.02 ng/ml, P < 0.05) and in vitro lymphocyte activation test (71.4%, 5/7 patients) compared with healthy control individuals. Furthermore, dapsone-specific cytotoxic T cells were significantly activated when co-cultured with HLA-B*13:01-expressing antigen presenting cells in the presence of dapsone (3.9-fold increase, compared with cells with no HLA-B*13:01 expression; P < 0.01). This study indicates that HLA-B*13:01 is strongly associated with dapsone DRESS and describes a functional role for the HLA-restricted immune mechanism induced by dapsone.
The Medication Risk of Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis in Asians: The Major Drug Causality and Comparison With the US FDA Label

Wang YH, Chen CB, Tassaneeyakul W, Saito Y, Aihara M, Choon SE, et al.

Clin. Pharmacol. Ther., 2019 01;105(1):112-120.
PMID: 29569740 DOI: 10.1002/cpt.1071

Specific ethnic genetic backgrounds are associated with the risk of Stevens-Johnson syndrome / toxic epidermal necrolysis (SJS/TEN) especially in Asians. However, there have been no large cohort, multiple-country epidemiological studies of medication risk related to SJS/TEN in Asian populations. Thus, we analyzed the registration databases from multiple Asian countries who were treated during 1998-2017. A total 1,028 SJS/TEN cases were identified with the algorithm of drug causality for epidermal necrolysis. Furthermore, those medications labeled by the US Food and Drug Administration (FDA) as carrying a risk of SJS/TEN were also compared with the common causes of SJS/TEN in Asian countries. Oxcarbazepine, sulfasalazine, COX-II inhibitors, and strontium ranelate were identified as new potential causes. In addition to sulfa drugs and beta-lactam antibiotics, quinolones were also a common cause. Only one acetaminophen-induced SJS was identified, while several medications (e.g., oseltamivir, terbinafine, isotretinoin, and sorafenib) labeled as carrying a risk of SJS/TEN by the FDA were not found to have caused any of the cases in the Asian countries investigated in this study.
Fulltext Pathogenic Variants in CEP85L Cause Sporadic and Familial Posterior Predominant Lissencephaly

Tsai MH, Muir AM, Wang WJ, Kang YN, Yang KC, Chao NH, et al.

Neuron, 2020 Apr 22;106(2):237-245.e8.
PMID: 32097630 DOI: 10.1016/j.neuron.2020.01.027

Lissencephaly (LIS), denoting a "smooth brain," is characterized by the absence of normal cerebral convolutions with abnormalities of cortical thickness. Pathogenic variants in over 20 genes are associated with LIS. The majority of posterior predominant LIS is caused by pathogenic variants in LIS1 (also known as PAFAH1B1), although a significant fraction remains without a known genetic etiology. We now implicate CEP85L as an important cause of posterior predominant LIS, identifying 13 individuals with rare, heterozygous CEP85L variants, including 2 families with autosomal dominant inheritance. We show that CEP85L is a centrosome protein localizing to the pericentriolar material, and knockdown of Cep85l causes a neuronal migration defect in mice. LIS1 also localizes to the centrosome, suggesting that this organelle is key to the mechanism of posterior predominant LIS.