This report describes intellectual disability, X-linked syndromic, Hedera type; an alternative designation of this disease is 'mental retardation, X-linked syndromic, Hedera type' (MRXSH). MRXSH exhibits X-linked recessive inheritance. This is one of several diseases associated with the human gene ATP6AP2. See the human disease model report 'neurological disorders, ATP6AP2-related' (FBhh0000787).
[updated Apr. 2018 by FlyBase; FBrf0222196]
Intellectual disability is characterized by impairments in intellectual functioning and adaptive behavior; symptoms must be present before a child becomes 18 years old (http://medical-dictionary.thefreedictionary.com/mental+retardation; 2016.01.19).
Intellectual disability can be subdivided into syndromic forms, characterized by cognitive impairment accompanied by dysmorphic features, malformations or neurological abnormalities, and nonsyndromic forms, characterized by cognitive impairment without additional features (Basel-Vanagaite, 2008; DOI: 10.1002/9780470015902.a0021454).
[INTELLECTUAL DEVELOPMENTAL DISORDER, X-LINKED, SYNDROMIC, HEDERA TYPE; MRXSH](https://omim.org/entry/300423)
[ATPase, H+ TRANSPORTING, LYSOSOMAL, ACCESSORY PROTEIN 2; ATP6AP2](https://omim.org/entry/300556)
Males exhibit mild to moderate mental retardation and epilepsy; global developmental delay from infancy is observed; generalized tonic-clonic seizures develop in most by 1 year. [from MIM:300423; 2017.09.29]
This form of syndromic X-linked mental retardation (MRXSH) is caused by mutation in the ATP6AP2 gene; transmission pattern is consistent with a monogenic X-linked recessive trait. [from MIM:300423; 2017.09.29]
The ATP6AP2 gene encodes a transmembrane protein that is an essential accessory component of the vacuolar ATPase required for lysosomal degradative functions and autophagy (summary by Korvatska et al., 2013; pubmed:23595882). [from MIM:300556; 2017.09.29]
One to one (1 human to 1 Drosophila).
