Developmental or degenerative – NR2E3 gene mutations in two patients with enhanced S cone syndrome

PurposeEnhanced S Cone Syndrome is a rare autosomal recessive disorder characterized clinically by an absence of rod function, a replacement of most L and M cone function by S cone activity (Goldmann-Favre Syndrome) and by variable degrees of retinal degeneration in different families. The causative gene, nuclear receptor subfamily 2, group E, member 3 (NR2E3), controls the developmental sequence for rods and cones. The purpose of this study was to compare the nature and implications of mutations in two subjects with Enhanced S Cone Syndrome who have significantly different degrees of degenerative damage.MethodsA direct sequencing approach was used to identify the mutations. Genomic DNA was amplified from all the exons of NR2E3 and used as a template for sequencing. Of the two families studied, Case 1 is of Persian ethnicity while Case 2 is Brazilian. A total of six individuals within the two families were studied.ResultsCase 1 (original propositus of the syndrome) has the characteristic developmental rod/cone abnormality with large amplitude electroretinogram responses and no retinal degeneration. She was homozygous for a novel mutation, c.[del196–201del6] (p.G66-C67del), which lies entirely within the P-box for this gene. By comparison, Case 2 had Goldmann-Favre Syndrome with retinal degeneration and low electroretinogram signals. She was a compound heterozygote for c.[119–2A>C]+[del194–202del9] (p.N65-C67del), mutations that have been reported previously. Her second mutation overlaps that of Case 1 within the P-box.ConclusionsThe novel in-frame homozygous deletion of Case 1, within the P-box motif of the DNA binding domain, caused a developmental abnormality without retinal degeneration. Case 2, with more traditional Goldmann-Favre Syndrome with retinal degeneration, was a compound heterozygote where one allele had a similar P-box deletion but the other was a splicing defect. Case 1 is the first reported homozygous deletion within the P-box. This is the first report of NR2E3 mutations in a Persian and a Brazilian family

European mtDNA Variants Are Associated With Differential Responses to Cisplatin, an Anticancer Drug: Implications for Drug Resistance and Side Effects.

Background: Cisplatin, a powerful antitumor agent, causes formation of DNA adducts, and activation of apoptotic pathways. Presently, cisplatin resistance develops in up to 70% of patients but the underlying molecular mechanism(s) are unclear and there are no markers to determine which patients will become resistant. Mitochondria play a significant role not only in energy metabolism but also retrograde signaling (mitochondria to nucleus) that modulates inflammation, complement, and apoptosis pathways. Maternally inherited mitochondrial (mt) DNA can be classified into haplogroups representing different ethnic populations that have diverse susceptibilities to diseases and medications. Methods: Transmitochondrial cybrids, where all cell lines possess identical nuclear genomes but either the H (Southern European) or J (Northern European) mtDNA haplogroups, were treated with cisplatin and analyzed for differential responses related to viability, oxidative stress, and expression levels of genes associated with cancer, cisplatin-induced nephrotoxicity and resistance, apoptosis and signaling pathways. Results: The cisplatin-treated-J cybrids showed greater loss of cell viability along with lower levels of reactive oxygen species and mitochondrial membrane potential compared to cisplatin-treated-H cybrids. After cisplatin treatment, J cybrids showed increased gene expression of BAX, CASP3, and CYP51A, but lower levels of SFRP1 compared to untreated-J cybrids. The cisplatin-treated-H cybrids had elevated expression of CDKN1A/P21, which has a role in cisplatin toxicity, compared to untreated-H cybrids. The cisplatin-treated H had higher transcription levels of ABCC1, DHRS2/HEP27, and EFEMP1 compared to cisplatin-treated-J cybrids. Conclusions: Cybrid cell lines that contain identical nuclei but either H mtDNA mitochondria or J mtDNA mitochondria respond differently to cisplatin treatments suggesting involvement of the retrograde signaling (from mitochondria to nucleus) in the drug-induced cell death. Varying toxicities and transcription levels of the H vs. J cybrids after cisplatin treatment support the hypothesis that mtDNA variants play a role in the expression of genes affecting resistance and side effects of cisplatin

Low frequency mitochondrial DNA heteroplasmy SNPs in blood, retina, and [RPE+choroid] of age-related macular degeneration subjects.

PurposeMitochondrial (mt) DNA damage is associated with age-related macular degeneration (AMD) and other human aging diseases. This study was designed to quantify and characterize mtDNA low-frequency heteroplasmy single nucleotide polymorphisms (SNPs) of three different tissues isolated from AMD subjects using Next Generation Sequencing (NGS) technology.MethodsDNA was extracted from neural retina, [RPE+choroid] and blood from three deceased age-related macular degeneration (AMD) subjects. Entire mitochondrial genomes were analyzed for low-frequency heteroplasmy SNPs using NGS technology that independently sequenced both mtDNA strands. This deep sequencing method (average sequencing depth of 30,000; range 1,000-100,000) can accurately differentiate low-frequency heteroplasmy SNPs from DNA modification artifacts. Twenty-three 'hot-spot' heteroplasmy mtDNA SNPs were analyzed in 222 additional blood samples.ResultsGermline homoplasmy SNPs that defined mtDNA haplogroups were consistent in the three tissues of each subject. Analyses of SNPs with <40% heteroplasmy revealed the blood had significantly greater numbers of heteroplasmy SNPs than retina alone (p≤0.05) or retina+choroid combined (p = 0.008). Twenty-three 'hot-spot' mtDNA heteroplasmy SNPs were present, with three being non-synonymous (amino acid change). Four 'hot-spot' heteroplasmy SNPs (m.1120C>T, m.1284T>C, m.1556C>T, m.7256C>T) were found in additional samples (n = 222). Five heteroplasmy SNPs (m.4104A>G, m.5320C>T, m.5471G>A, m.5474A>G, m.5498A>G) declined with age. Two heteroplasmy SNPs (m.13095T>C, m.13105A>G) increased in AMD compared to Normal samples. In the heteroplasmy SNPs, very few transversion mutations (purine to pyrimidine or vice versa, associated with oxidative damage) were found and the majority were transition changes (purine to purine or pyrimidine to pyrimidine, associated with replication errors).ConclusionWithin an individual, the blood, retina and [RPE+choroid] contained identical homoplasmy SNPs representing inherited germline mtDNA haplogroup. NGS methodology showed significantly more mtDNA heteroplasmy SNPs in blood compared to retina and [RPE+choroid], suggesting the latter tissues have substantial protection. Significantly higher heteroplasmy levels of m.13095T>C and m.13105A>G may represent potential AMD biomarkers. Finally, high levels of transition mutations suggest that accumulation of heteroplasmic SNPs may occur through replication errors rather than oxidative damage

Low frequency mitochondrial DNA heteroplasmy SNPs in blood, retina, and [RPE+choroid] of age-related macular degeneration subjects.

PurposeMitochondrial (mt) DNA damage is associated with age-related macular degeneration (AMD) and other human aging diseases. This study was designed to quantify and characterize mtDNA low-frequency heteroplasmy single nucleotide polymorphisms (SNPs) of three different tissues isolated from AMD subjects using Next Generation Sequencing (NGS) technology.MethodsDNA was extracted from neural retina, [RPE+choroid] and blood from three deceased age-related macular degeneration (AMD) subjects. Entire mitochondrial genomes were analyzed for low-frequency heteroplasmy SNPs using NGS technology that independently sequenced both mtDNA strands. This deep sequencing method (average sequencing depth of 30,000; range 1,000-100,000) can accurately differentiate low-frequency heteroplasmy SNPs from DNA modification artifacts. Twenty-three 'hot-spot' heteroplasmy mtDNA SNPs were analyzed in 222 additional blood samples.ResultsGermline homoplasmy SNPs that defined mtDNA haplogroups were consistent in the three tissues of each subject. Analyses of SNPs with T, m.1284T>C, m.1556C>T, m.7256C>T) were found in additional samples (n = 222). Five heteroplasmy SNPs (m.4104A>G, m.5320C>T, m.5471G>A, m.5474A>G, m.5498A>G) declined with age. Two heteroplasmy SNPs (m.13095T>C, m.13105A>G) increased in AMD compared to Normal samples. In the heteroplasmy SNPs, very few transversion mutations (purine to pyrimidine or vice versa, associated with oxidative damage) were found and the majority were transition changes (purine to purine or pyrimidine to pyrimidine, associated with replication errors).ConclusionWithin an individual, the blood, retina and [RPE+choroid] contained identical homoplasmy SNPs representing inherited germline mtDNA haplogroup. NGS methodology showed significantly more mtDNA heteroplasmy SNPs in blood compared to retina and [RPE+choroid], suggesting the latter tissues have substantial protection. Significantly higher heteroplasmy levels of m.13095T>C and m.13105A>G may represent potential AMD biomarkers. Finally, high levels of transition mutations suggest that accumulation of heteroplasmic SNPs may occur through replication errors rather than oxidative damage

Hereditary motor and sensory neuropathy type VI with optic atrophy

To present the detailed clinical findings of a large family with hereditary motor and sensory neuropathy type VI (HMSN VI), a syndrome featuring optic atrophy. Observational case series. A detailed history was obtained and physical examination was made of the extended family of the proband for evidence of neurologic dysfunction. The OPA1 gene was screened for mutations by direct DNA sequencing. Twelve of 97 family members examined are affected with signs of HMSN VI. Three other members have either optic atrophy or peripheral neuropathy, thus allowing an appreciation of the full clinical spectrum of disease. No mutations were found in the OPA1 gene. This family demonstrates the variable expressivity of this disorder as well as incomplete penetrance. This is the largest known family with HMSN VI. No association was found with changes in the OPA1 gene

New noncoding base pair mutation at the identical locus as the original NCMD/MCDR1 in a Mexican family, suggesting a mutational hotspot

Purpose:To clinically and molecularly study a newly found family with North Carolina macular dystrophy (NCMD/MCDR1) from Mexico. Methods:This retrospective study comprised 6 members of a 3-generation Mexican family with NCMD. Clinical ophthalmic examinations, including fundus imaging, spectral-domain optical coherence tomography, electroretinography, and electrooculography, were performed. Genotyping with polymorphic markers in the MCDR1 region was performed to determine haplotypes. Whole-genome sequencing (WGS) was performed followed by variant filtering and copy number variant analysis. Results:Four subjects from 3 generations were found to have macular abnormalities. The proband presented with lifelong bilateral vision impairment with bilaterally symmetric vitelliform Best disease-like appearing macular lesions. Her 2 children had bilateral large macular coloboma-like malformations, consistent with autosomal dominant NCMD. The 80-year-old mother of the proband had drusen-like lesions consistent with grade 1 NCMD. WGS and subsequent Sanger sequencing found a point mutation at chr6:99593030G>C (hg38) in the noncoding region of the DNase I site thought to be a regulatory element of the retinal transcription factor gene PRDM13. This mutation is the identical site/nucleotide as in the original NCMD family (#765) but is a guanine to cytosine change rather than a guanine to thymine mutation, as found in the original NCMD family. Conclusions:We report a new noncoding mutation at the same locus (chr6:99593030G>C) involving the same DNase I site regulating the retinal transcription factor gene PRDM13. This suggests that this site, chr6:99593030, is a mutational hotspot

Contemporary Collaborative Consumption : Trust and Reciprocity Revisited

This book provides critical perspectives on contemporary collaborative consumption, a recent societal phenomenon shaking up previously fixed socio-economic categories such as the producer and the consumer. The contributors discuss the role of trust and reciprocity in collaborative consumption through seven case studies. The chapters advance debates on the contradictions of positioning collaborative consumption as possible solutions for a more sustainable development and exacerbating new forms of inequalities and injustice. The book contributes a nuanced appraisal of social and economic activity for reflecting socio-technological changes in contemporary societies