Cutaneous T‐cell lymphomas (CTCLs) are telomerase‐positive tumors expressing hTERT, although neither gene rearrangement/amplification nor promoter hotspot mutations could explain the hTERT ...re‐expression. As the hTERT promoter is rich in CpG, we investigated the contribution of epigenetic mechanisms in its re‐expression. We analyzed hTERT promoter methylation status in CTCL cells compared with healthy cells. Gene‐specific methylation analyses revealed a common methylation pattern exclusively in tumor cells. This methylation pattern encompassed a hypermethylated distal region from −650 to −150 bp and a hypomethylated proximal region from −150 to +150 bp. Interestingly, the hypermethylated region matches with the recently named TERT hypermethylated oncogenic region (THOR). THOR has been associated with telomerase reactivation in many cancers, but it has so far not been reported in cutaneous lymphomas. Additionally, we assessed the effect of THOR on two histone deacetylase inhibitors (HDACi), romidepsin and vorinostat, both approved for CTCL treatment and a DNA methyltransferase inhibitor (DNMTi) 5‐azacytidine, unapproved for CTCL. Contrary to our expectations, the findings reported herein revealed that THOR methylation is relatively stable under these epigenetic drugs' pressure, whereas these drugs reduced the hTERT gene expression.
Cutaneous T‐cell lymphomas (CTCLs) represent a group of lymphoproliferative disorders arising from the skin. CTCLs are characterized by hTERT gene expression despite the lack of hTERT amplifications or rearrangements. Here, we investigated hTERT promoter methylation and associated TERT hypermethylated oncogenic region (THOR) with hTERT reactivation in CTCL. Additionally, we evaluated THOR methylation and hTERT expression after treatment with epigenetic drugs. Altogether, our study offers a better understanding of the response to epigenetic drugs in patients with CTCL.
Cystic fibrosis is the most common life‐limiting autosomal recessive disease in western countries with an incidence of 1:2500 in United States and 1:1000 in some European countries. Similar ...incidences were noted for the Middle East with variations from 1 in 2560 to 1 in 15,876 according to the degree of consanguinity. This is a preliminary systematic study that aims to assess the incidence and carrier rate of cystic fibrosis in the Middle Eastern Lebanese population; known for a high frequency of consanguinity. One hundred thirteen DNA samples were collected from neonatal blood cards obtained from newborns to healthy unrelated families with no previous history of Cystic fibrosis. Screening for Cystic Fibrosis‐causing pathogenic variants was performed using next generation sequencing, and 17 different single nucleotide variants were detected, including six pathogenic and likely pathogenic. 5.5%–7% newborns were found to be carriers of a variant strongly suggestive of pathogenicity and comparable to published literature worldwide. This pilot analysis highlights the challenging interpretation of CFTR variants in a country underrepresented by large ethnic population analyses, and stresses the importance of premarital screening programs for Cystic fibrosis.
Nonsyndromic hearing loss is genetically heterogeneous. Despite comprehensive genetic testing, many cases remain unsolved because the clinical significance of identified variants is uncertain or ...because biallelic pathogenic variants are not identified for presumed autosomal recessive cases. Common synonymous variants are often disregarded. Determining the pathogenicity of synonymous variants may improve genetic diagnosis. We report a synonymous variant c.9861 C > T/p.(Gly3287=) in MYO15A in homozygosity or compound heterozygosity with another pathogenic or likely pathogenic MYO15A variant in 10 unrelated families with nonsyndromic sensorineural hearing loss. Biallelic variants in MYO15A were identified in 21 affected and were absent in 22 unaffected siblings. A mini-gene assay confirms that the synonymous variant leads to abnormal splicing. The variant is enriched in the Ashkenazi Jewish population. Individuals carrying biallelic variants involving c.9861 C > T often exhibit progressive post-lingual hearing loss distinct from the congenital profound deafness typically associated with biallelic loss-of-function MYO15A variants. This study establishes the pathogenicity of the c.9861 C > T variant in MYO15A and expands the phenotypic spectrum of MYO15A-related hearing loss. Our work also highlights the importance of multicenter collaboration and data sharing to establish the pathogenicity of a relatively common synonymous variant for improved diagnosis and management of hearing loss.
Unique pathogenic mutations in BRCA1 and 2 genes have been reported in different populations of patients originating from the Middle East region. Limited data are available for the Iraqi population. ...For many reasons a large number of Iraqi patients present to Lebanon for medical care. This is the first report of BRCA full gene sequencing conducted in a cohort of high-risk patients originating from Iraq.
This is a retrospective review of Iraqi patients diagnosed with breast or ovarian cancer referred for BRCA mutation testing at the American University of Beirut from January 2012 to October 2018.
Of the 42 Iraqi women who underwent genetic testing at our institution, 3 BRCA pathogenic variants were found. Two mutations in BRCA1 c.224_227delAAAG and c.5431C > T and one mutation in BRCA2 c.5576_5579delTTAA were identified. Three other patients had sequence changes considered as variants of undetermined significance.
In this cohort of high-risk patients, one out of the three pathogenic BRCA variants detected has not previously been reported in the Middle Eastern population. Further studies are required to delineate the spectrum of BRCA mutations in the Iraqi population.
Sézary syndrome (SS) is an aggressive leukemic variant of cutaneous T-cell lymphomas (CTCL) in which the human Telomerase Reverse Transcriptase (
hTERT
) gene is re-expressed. Current available ...treatments do not provide long-term response. We previously reported that Histone deacetylase inhibitors (HDACi, romidespin and vorinostat) and a DNA methyltransferase inhibitor (DNMTi, 5-azacytidine) can reduce
hTERT
expression without altering the methylation level of
hTERT
promoter. Romidepsin and vorinostat are approved for CTCL treatment, while 5-azacytidine is approved for the treatment of several hematological disorders, but not for CTCL. Here, using the soft agar assay, we analyzed the functional effect of the aforementioned epidrugs on the clonogenic capacities of Sézary cells. Our data revealed that, besides
hTERT
downregulation, epidrugs’ pressure reduced the proliferative and the tumor formation capacities in Sézary cells
in vitro
.
Telomeric Repeat-containing RNA (TERRA) are long non-coding RNAs transcribed from telomeric DNA sequences from multiple chromosome ends. Major research efforts have been made to understand TERRA ...roles and functions in several physiological and pathological processes. We summarize herein available data regarding TERRA's roles in human cells and we report the first investigation in cutaneous T-cells lymphomas (CTCL) using real-time PCR. Among the TERRA analysed, our data suggest a particular role for TERRA 16p downregulation and TERRA 11q upregulation in CTCL lymphomagenesis.
Apparently balanced chromosomal rearrangements in individuals with major congenital anomalies represent natural experiments of gene disruption and dysregulation. These individuals can be studied to ...identify novel genes critical in human development and to annotate further the function of known genes. Identification and characterization of these genes is the goal of the Developmental Genome Anatomy Project (DGAP). DGAP is a multidisciplinary effort that leverages the recent advances resulting from the Human Genome Project to increase our understanding of birth defects and the process of human development. Clinically significant phenotypes of individuals enrolled in DGAP are varied and, in most cases, involve multiple organ systems. Study of these individuals' chromosomal rearrangements has resulted in the mapping of 77 breakpoints from 40 chromosomal rearrangements by FISH with BACs and fosmids, array CGH, Southern-blot hybridization, MLPA, RT-PCR, and suppression PCR. Eighteen chromosomal breakpoints have been cloned and sequenced. Unsuspected genomic imbalances and cryptic rearrangements were detected, but less frequently than has been reported previously. Chromosomal rearrangements, both balanced and unbalanced, in individuals with multiple congenital anomalies continue to be a valuable resource for gene discovery and annotation.
Background
Citrullinemia type 1 (CTLN1) is a rare autosomal recessive disease caused by argininosuccinate synthetase (ASS) deficiency. Manifestations vary from the acute neonatal or “classic” form to ...a milder, late‐onset, or “unconventional” form. To date, more than 93 variants in the ASS1 gene located on chromosome 9q43.11 (OMIM #215700) are reportedly responsible for CTLN1. Their incidence and distribution vary according to geographic origins and ethnicity, and a correlation, although not clearly delineated, has been established between the genotype and the phenotype of the disease. Though, in the Middle East, national descriptions of CTLN1 are still lacking.
Methods
A total of ten unrelated Middle Eastern families, five Lebanese, two Syrians, and three Iraqis with citrullinemia index cases, were included in this study. Upon informed consent, DNA was extracted from the whole blood of the index patients as well as their parents and siblings. Genetic analysis was carried out by Sanger sequencing of the ASS1 gene.
Results
Seven different variants were identified. Two novel variants, c.286C>A (p.(Pro96Thr), RNA not analyzed) in exon 5 and deletion c.685_688+6del(p.(Lys229Glyfs*4), RNA not analyzed) in exon 10, were found in one Lebanese and one Syrian family, respectively, and were correlated with early‐onset and severe clinical presentation. Five other known variants: c.535T>C (p.(Trp179Arg), RNA not analyzed) in exon 8, c.787G>A (p.(Val263Met), RNA not analyzed) in exon 12, c.847G>A (p.(Glu283Lys), RNA not analyzed) in exon 13, c.910C>T (p.(Arg304Trp), RNA not analyzed) in exon 13, and c.1168G>A (p.(Gly390Arg), RNA not analyzed) in exon 15, were found in Lebanese, Syrian, and Iraqi families, and were associated with diverse clinical presentations.
Conclusion
Two novel variants and five known variants were found in a total of ten unrelated Middle Eastern families.
A total of ten unrelated Middle Eastern families were included in this study. DNA was extracted from the whole blood of the index patients as well as their parents and siblings. Genetic analysis was carried out by Sanger sequencing of ASS1 gene. Two novel variants and five known variants were found in a total of ten unrelated Middle Eastern families.
Split-hand-split-foot malformation (SHFM) is a rare condition that occurs in 1 in 8500-25,000 newborns and accounts for 15% of all limb reduction defects. SHFM is heterogeneous and can be isolated, ...associated with other malformations, or syndromic. The mode of inheritance is mostly autosomal dominant with incomplete penetrance, but can be X-linked or autosomal recessive. Seven loci are currently known: SHFM1 at 7q21.2q22.1 (DLX5 gene), SHFM2 at Xq26, SHFM3 at 10q24q25, SHFM4 at 3q27 (TP63 gene), SHFM5 at 2q31 and SHFM6 as a result of variants in WNT10B (chromosome 12q13). Duplications at 17p13.3 are seen in SHFM when isolated or associated with long bone deficiency. Tandem genomic duplications at chromosome 10q24 involving at least the DACTYLIN gene are associated with SHFM3. No point variant in any of the genes residing within the region has been identified so far, but duplication of exon 1 of the BTRC gene may explain the phenotype, with likely complex alterations of gene regulation mechanisms that would impair limb morphogenesis. We report on 32 new index cases identified by array-CGH and/or by qPCR, including some prenatal ones, leading to termination for the most severe. Twenty-two cases were presenting with SHFM and 7 with monodactyly only. Three had an overlapping phenotype. Additional findings were identified in 5 (renal dysplasia, cutis aplasia, hypogonadism and agenesis of corpus callosum with hydrocephalus). We present their clinical and radiological findings and review the literature on this rearrangement that seems to be one of the most frequent cause of SHFM.
Meckel-Gruber syndrome (MKS, OMIM #249000) is a multiple congenital malformation syndrome that represents the severe end of the ciliopathy phenotypic spectrum. Despite the relatively common ...occurrence of this syndrome among Arabs, little is known about its genetic architecture in this population. This is a series of 18 Arab families with MKS, who were evaluated clinically and studied using autozygome-guided mutation analysis and exome sequencing. We show that autozygome-guided candidate gene analysis identified the underlying mutation in the majority (n=12, 71%). Exome sequencing revealed a likely pathogenic mutation in three novel candidate MKS disease genes. These include C5orf42, Ellis-van-Creveld disease gene EVC2 and SEC8 (also known as EXOC4), which encodes an exocyst protein with an established role in ciliogenesis. This is the largest and most comprehensive genomic study on MKS in Arabs and the results, in addition to revealing genetic and allelic heterogeneity, suggest that previously reported disease genes and the novel candidates uncovered by this study account for the overwhelming majority of MKS patients in our population.
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