SDHD (succinate-ubiquinone oxidoreductase subunit D, a mitochondrial complex II gene) showed paternal expression in four glomus tumours (nonchromaffin paragangliomas), in the absence of apparent loss of heterozygosity (Badenhop RF et al, 2001), but biallelic expression in lymphocytes, 2 adult brain, 3 fetal brains and 1 fetal kidney (Badenhop RF et al, 2001; Baysal BE et al, 2000).
Mutations of SDHD cause hereditary paraganglioma type 1 (glomus tumours) which are always inherited from carrier fathers (Baysal BE et al, 1997; Mariman EC et al, 1995; van der Mey AG et al, 1989; Milunsky J et al, 1997).
Hensen EF et al, 2004 showed deletion of the entire maternal chromosome 11 in all nineteen cases of paraganglioma, and suggest that the apparent imprinting of SDHD is attributable to the need to delete both a maternally expressed tumour suppressor gene elsewhere on chromosome 11 (eg, 11p15), and the wildtype copy of SDHD. Yeap PM et al (2011) confirmed that tumour formation requires the loss of both the wild-type SDHD allele and maternal 11p15, leading to the predominant but not exclusive pattern of disease inheritance after paternal SDHD transmission.
Margetts CD et al, 2005 found loss of the maternal allele in VHL-associated (n = 3) and sporadic phaeochromocytomas (n = 7) without SDHD mutations, suggesting that 11p loss reflects the involvement of other imprinted 11p15.5 genes and providing evidence against imprinting of SDHD itself.
Baysal et al, (2011) claim evidence for imprinting at a non-coding gene, termed UPGL (Untranslated in ParaGanglioma Locus) situated 206 kb telomeric to the SDHD locus. They report allele specific methylation in the adrenal cortex of four out of five fetuses. In one sample the more methylated allele was identified as maternal. Allelic expression imbalance for UPGL was detected in one of seven fetuses; the other six showed biallelic expression.
Morcos L et al, (2011) found no evidence of allelic expression bias in lymphoblast cell lines.
Baran Y et al (2015) found no evidence of imprinting of SDHD in multiple adult tissues (using RNA-seq).





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