Taxon: Human

Chromosome: 08

Location:

Gene: "UPD"

Description: A case of maternal UPD was associated with an early onset ileal carcinoid tumor (Karanjawalaa ZE, et al. 2000).
A case of late-infantile-onset neuronal ceroid lipofuscinosis (LINCL) was reported to be due to maternal UPD of chromosome 8, where two mutations in the CLN8 gene were unmasked (Vantaggiato C et al 2009).
Through a SNP genotyping microarray study, a case of maternal UPD of chromosome 8 was identified. The proband had a prominent forehead, plagiocephaly, hypertelorism, low set ears, short toe, inside ear prominence and pneumothorax (Papenhausen P et al 2011).
Varon R et al (2007) report a case of Nijmegen breakage syndrome (NBS) due to maternal isodisomy of chromosome 8.

A case of lipoprotein-lipase (LPL) deficiency due to a homozygous mutation in the LPL gene was discovered in a female proband with paternal isodisomy of chromosome 8. Apart from this condition the proband was phenotypically normal, suggesting that normal development can occur with two copies of chromosome 8 (Benlian P et al 1996).
Matsubara K et al (2014) report a case of paternal UPD of chromosome 8 leading to homozygosity of a CYP11B1 mutation in a patient with congenital adrenal hyperplasia (CAH).
Paternal UPD of chromosome 8 has been reported in proband with spinal muscular atrophy and progressive myoclonic epilepsy (Giráldez BG et al 2015).

Category: Disomy (UPD)

Taxon: Human

Chromosome: 08

Location:

Gene: Alcoholism susceptibility

Description: There is evidence of linkage of maternal alleles on chromosome 8 (and 1) with alcoholism (Paterson AD et al, 1999; Wyszynski DF et al, 1999) .

Category: Parental effect

Taxon: Human

Chromosome: 08

Location: 10.9 cM

Gene: Alcoholism

Description: Parent-of-origin effects were observed in sib-pair analysis of 105 families with recurrent alcoholism. The study revealed an increased sharing of the marker D8S280 in affected siblings (P = 0.0001 for ALDX2 class alcoholism) only when the allele was transmitted maternally (Wyszynski DF et al, 1999).

Category: Parental effect

Taxon: Human

Chromosome: 08

Location: 14.3 cM

Gene: Alcoholism

Description: Parent-of-origin effects were observed in sib-pair analysis of 105 families with recurrent alcoholism. The study revealed an increased sharing of the marker D8S1715 in affected siblings (P <= 0.0001 for ALDX1 and ALDX3 and P = 0.0006 for ALDX2 class alcoholism) only when the allele was transmitted maternally (Wyszynski DF et al, 1999).

Category: Parental effect

Taxon: Human

Chromosome: 08

Location: 85.7 cM

Gene: Alcoholism

Description: Parent-of-origin effects were observed in sib-pair analysis of 105 families with recurrent alcoholism. The study revealed an increased sharing of the marker D8S1988 in affected siblings (P = 0.0003 and P = 0.0005 for ALDX1 and ALDX3 class alcoholism respectivley) only when the allele was transmitted maternally (Wyszynski DF et al, 1999).

Category: Parental effect

Taxon: Human

Chromosome: 08

Location: 8p11.21

Gene: IDO1 (provisional data)

Description: IDO1 (indoleamine 2,3-dioxygenase 1) shows high sperm methylation and partial methylation in the placenta suggesting that it may be imprinted (Spinelli P et al, 2019). Ido1 and Ido2 are imprinted and maternally expressed in the mouse placenta (Spinelli P et al, 2019).

Category: Imprinted genes

Taxon: Human

Chromosome: 08

Location: 8p23

Gene: DLGAP2

Description: DLGAP2 (discs, large (Drosophila) homolog-associated protein 2; a membrane associated guanylate kinase) was paternally expressed in 8 fetal testes, in which all 4 isoforms were imprinted. However, isoforms 24 and 26 showed "some evidence of imprinting relaxation" in 1 of 6, and 2 of 8 samples respectively (Luedi PP et al, 2007). DLGAP2 was not imprinted in fetal whole brain.
Morcos L et al, (2011) found no evidence of allelic expression bias in lymphoblast and fibroblast cell lines.

Category: Imprinted genes

Taxon: Human

Chromosome: 08

Location: 8q21.2

Gene: Differentially methylated region

Description: This region contains a CpG island that is differentially methylated in hydatidiform moles (paternal origin) and complete ovarian teratomas (maternal origin) (Strichman-Almashanu LZ et al, 2002).

Category: DMR or ICR

Taxon: Human

Chromosome: 08

Location: 8q24.22

Gene: ZFAT

Description: ZFAT (zinc finger and AT hook domain containing) showed monoallelic expression in at least 9 placentas investigated, and in two cases the expressed allele could be determined and was paternal. However, biallelic expression was observed in human lymphocytes, endometrial tissue and thyroid tumours. None of the three CpG rich regions near ZFAT showed differential methylation. Biallelic expression was found in mouse E14.5 placentas and in bovine placentas (Barbaux S et al, 2012). Metsula T et al (2014) confirmed monoallelic expression but reported opposite parents-of-origin in two families. In contrast they reported that their results for ZFAT-AS1 were consistent with imprinted paternal expression but only three informative families were available.

Category: Other

Taxon: Human

Chromosome: 08

Location: 8q24.22

Gene: ZFAT-AS1 (provisional)

Description: ZFAT-AS1 showed monoallelic expression in at least 10 placentas investigated, and in three cases the expressed allele could be determined and was paternal. However, biallelic expression was observed in thyroid tumours (Barbaux S et al, 2012).
Metsula T et al (2014) reported monoallelic paternal expression in 3/3 informative families. However, they also reported random monoallelic expression of ZFAT itself.
Since it seems unlikely that ZFAT is imprinted then the imprinted expression of ZFAT-AS1 also seems unlikely despite the reported 6/6 cases showing paternal expression.

Category: Imprinted genes

Taxon: Human

Chromosome: 08

Location: 8q24.3

Gene: Syntenic to mouse Peg13

Description: Syntenic location of mouse Peg13 that is imprinted in mouse. A homologous transcript has not been identified in human (Smith RJ et al, 2003).

Category: Other

Taxon: Human

Chromosome: 08

Location: 8q24.3

Gene: KCNK9

Description: KCNK9 (potassium channel, subfamily K, member 9) is expressed predominantly in the brain. It showed strict or predominant monoallelic expression in 7 heterozygous human fetal brain samples. Maternal expression could be demonstrated in two cases (Ruf D et al, 2007).
Luedi PP et al (2007) found exclusive maternal expression in 9 fetal brains (gestation 63-98 d).
Barel O et al. (2008) described a kindred with maternally inherited mental retardation dysmorphism syndrome (Birk Barel sundrome) caused by a mutation in KCNK9.
In mouse, Kcnk9 is about 260 kb downstream of Peg13 which has a germline maternally-methylated DMR. However, in humans a Peg13 orthologue has not been identified and no DMRs were identified by Ruf et al.
Morcos L et al, (2011) found no evidence of allelic expression bias in lymphoblast and fibroblast cell lines.

Category: Imprinted genes

Taxon: Human

Chromosome: 08

Location: 8q24.3

Gene: TRAPPC9

Description: TRAPPC9 (trafficking protein particle complex 9) was reported to show biased paternal expression in human fibroblasts (Morcos L et al, 2011).
An intronic region of TRAPPC9 show parent-of-origin specific methylation (Gertz J et al, 2011).
Biased paternal expression was confirmed but was reported to be a probable false positive result due to sense overlap with Peg13 (Andergassen D et al, 2015).

Category: Other

Taxon: Human

Chromosome: 08

Location: 8q24.3

Gene: Birk-Barel mental retardation dysmorphism syndrome / KCNK9 imprinting syndrome

Description: Barel O et al (2008) described a kindred with maternally inherited mental retardation dysmorphism syndrome (Birk-Barel syndrome) caused by a specific mutation (p.Gly236Arg) in the imprinted, maternally expressed, gene KCNK9. The syndrome has been reviewed by Zadeh N and Graham JM (2017).

Category: Imprinting disorder