TY  - JOUR
A1  - Hofrichter, Michaela A. H.
A1  - Mojarad, Majid
A1  - Doll, Julia
A1  - Grimm, Clemens
A1  - Eslahi, Atiye
A1  - Hosseini, Neda Sadat
A1  - Rajati, Mohsen
A1  - Müller, Tobias
A1  - Dittrich, Marcus
A1  - Maroofian, Reza
A1  - Haaf, Thomas
A1  - Vona, Barbara
T1  - The conserved p.Arg108 residue in S1PR2 (DFNB68) is fundamental for proper hearing: evidence from a consanguineous Iranian family
JF  - BMC Medical Genetics
N2  - Background:
Genetic heterogeneity and consanguineous marriages make recessive inherited hearing loss in Iran the second most common genetic disorder. Only two reported pathogenic variants (c.323G>C, p.Arg108Pro and c.419A>G, p.Tyr140Cys) in the S1PR2 gene have previously been linked to autosomal recessive hearing loss (DFNB68) in two Pakistani families. We describe a segregating novel homozygous c.323G>A, p.Arg108Gln pathogenic variant in S1PR2 that was identified in four affected individuals from a consanguineous five generation Iranian family.

Methods:
Whole exome sequencing and bioinformatics analysis of 116 hearing loss-associated genes was performed in an affected individual from a five generation Iranian family. Segregation analysis and 3D protein modeling of the p.Arg108 exchange was performed.

Results:
The two Pakistani families previously identified with S1PR2 pathogenic variants presented profound hearing loss that is also observed in the affected Iranian individuals described in the current study. Interestingly, we confirmed mixed hearing loss in one affected individual. 3D protein modeling suggests that the p.Arg108 position plays a key role in ligand receptor interaction, which is disturbed by the p.Arg108Gln change.

Conclusion:
In summary, we report the third overall mutation in S1PR2 and the first report outside the Pakistani population. Furthermore, we describe a novel variant that causes an amino acid exchange (p.Arg108Gln) in the same amino acid residue as one of the previously reported Pakistani families (p.Arg108Pro). This finding emphasizes the importance of the p.Arg108 amino acid in normal hearing and confirms and consolidates the role of S1PR2 in autosomal recessive hearing loss.
KW  - 3D modeling
KW  - autosomal recessive non-synstromic hearing loss
KW  - DFNB68
KW  - mixed hearing loss
KW  - whole exome sequencing
KW  - S1PR2
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-175755
VL  - 19
IS  - 81
ER  - 
TY  - JOUR
A1  - Flunkert, Julia
A1  - Maierhofer, Anna
A1  - Dittrich, Marcus
A1  - Müller, Tobias
A1  - Horvath, Steve
A1  - Nanda, Indrajit
A1  - Haaf, Thomas
T1  - Genetic and epigenetic changes in clonal descendants of irradiated human fibroblasts
JF  - Experimental Cell Research
N2  - To study delayed genetic and epigenetic radiation effects, which may trigger radiation-induced carcinogenesis, we have established single-cell clones from irradiated and non-irradiated primary human fibroblasts. Stable clones were endowed with the same karyotype in all analyzed metaphases after 20 population doublings (PDs), whereas unstable clones displayed mosaics of normal and abnormal karyotypes. To account for variation in radiation sensitivity, all experiments were performed with two different fibroblast strains. After a single X-ray dose of 2 Gy more than half of the irradiated clones exhibited radiation-induced genome instability (RIGI). Irradiated clones displayed an increased rate of loss of chromosome Y (LOY) and copy number variations (CNVs), compared to controls. CNV breakpoints clustered in specific chromosome regions, in particular 3p14.2 and 7q11.21, coinciding with common fragile sites. CNVs affecting the FHIT gene in FRA3B were observed in independent unstable clones and may drive RIGI. Bisulfite pyrosequencing of control clones and the respective primary culture revealed global hypomethylation of ALU, LINE-1, and alpha-satellite repeats as well as rDNA hypermethylation during in vitro ageing. Irradiated clones showed further reduced ALU and alpha-satellite methylation and increased rDNA methylation, compared to controls. Methylation arrays identified several hundred differentially methylated genes and several enriched pathways associated with in vitro ageing. Methylation changes in 259 genes and the MAP kinase signaling pathway were associated with delayed radiation effects (after 20 PDs). Collectively, our results suggest that both genetic (LOY and CNVs) and epigenetic changes occur in the progeny of exposed cells that were not damaged directly by irradiation, likely contributing to radiation-induced carcinogenesis. We did not observe epigenetic differences between stable and unstable irradiated clones. The fact that the DNA methylation (DNAm) age of clones derived from the same primary culture varied greatly suggests that DNAm age of a single cell (represented by a clone) can be quite different from the DNAm age of a tissue. We propose that DNAm age reflects the emergent property of a large number of individual cells whose respective DNAm ages can be highly variable.
KW  - copy number variation (CNV)
KW  - delayed radiation effects
KW  - DNA methylation (DNAm) age
KW  - global DNA methylation
KW  - loss of chromosome Y (LOY);
KW  - methylation array analysis
KW  - radiation-induced genome instability (RIGI)
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-228177
VL  - 370
ER  -