SGCE (sarcoglycan epsilon) shares a promoter CpG island with PEG10. The transcription start sites of
these two genes are 115 bp apart (in opposite directions). The promoter CpG island is maternally
methylated in peripheral blood
leukocytes. In UPD7
cell lines only a weak RT-PCR signal was observed in matUPD7 whereas a strong signal was seen in
patUPD7 lines suggesting preferential paternal expression (Grabowski
M et al. 2003).
Morcos L et al (2011) claimed to validate
paternal expression of SGCE in lymphoblastoid cell lines, but only two families trios were studied
and specific data were not presented.
SGCE is involved in dystrophin-associated glycoprotein assembly in striated muscles and is
associated with myoclonus dystonia (MD) which shows autosomal dominant inheritance with reduced
penetrance upon maternal transmission. Among 6 families with SGCE mutations, 49 of 62 clinically
affected individuals inherited the disease paternally, whereas 4 inherited it maternally (9
unknown). Of 18 asymptomatic carriers, 14 inherited the mutation maternally and 3 paternally (1
A et al. 2001). This inheritance pattern suggests preferential paternal expression of SGCE as
reported in mouse Sgce (Piras
G et al. 2000).
Two families with unaffected parents and affected offspring were analyzed for inheritance and
expression of the SGCE gene. In one family, both offspring were affected and showed expression from
paternally inherited mutant alleles only. In the second family the single affected child also had a
paternally inherited mutant allele, but showed biallelic expression that was associated with partial
loss of methylation at several CpG nucleotides in the promoter region of SGCE (Muller
B et al. 2002).
A maternally methylated germline DMR overlaps exon1 of PEG10 and SGCE
(chr7:94122795-94124463 NCBI build 36.1) (Ono
R, et al. 2003).
A case of myoclonus-dystonia due to maternal uniparental disomy of 7p11.2-7q11.21, including SGCE,
was used to demonstrate biallelic methylation and lack of expression in blood, consistent with
exclusive paternal expression of SGCE (Guettard E et al, 2008).