A healthy male with a maternal UPD of chromosome 22 has been reported. The proband was discovered to have a
Robertsonian 22/22 translocation after being referred for cytogenetic studies due to his wifeís repeat spontaneous
abortions (Schinzel AA et al 1994).
Two cases of transmission of a Robertsonian 22/22 translocation from mother to daughter have been reported. Both
women in each case had multiple repeat spontaneous abortions (Kirkels VG et al 1980; Palmer CG et al 1980).
A case of recessive congenital methemoglobinaemia (RCM) has been reported due to maternal uniparental
heterodisomy of chromosome 22 with segmental isodisomy. RCM is is caused by NADH cytochrome b5 reductase
(cb5r) deficiency due to a mutation in the CYB5R3 gene (Huang YH et al 2012).
Two cases of infantile neuroaxonal dystrophy (INAD) due to maternal UPD that reveal mutations in the phospholipase
A2 group 6 (PLA2G6) gene have been identified (Zhang
P et al 2013; Solomons J et al 2014).
Maternal UPD of chromosome 22 was identified in a patient with megalencephalic leukoencephalopathy with
subcortical cysts (MLC) (Cao B et al 2016).
A case of paternal UPD has been reported in a phenotypically normal male who inherited his fatherís Robertsonian
translocation (der(22;22)(q10;q10)) (Ouldim K et al
Chopade DK et al (2014) report a similar case
where a daughter inherited her fatherís balanced translocation (t(22q;22q)).
Niida Y et al (2012) report a case of metachromatic
leukodystrophy (MLD) due to paternal UPD of chromosome 22. UPD revealed homozygosity in the ARSA gene that
codes for arylsulfatase.
Parent-of-origin effects of chromosome 22 are considered unlikely.