Three truncating variants were recurrent (UBE2NL:266T>G, L89*; MAGEE2: 358G>T, E120* and GTPBP6: 118C>T, Q40*) (Table 3). These were found in controls at a similar prevalence to XLMR-affected families and so are unlikely to be responsible for mental retardation in the families in which they were identified. They each, however, are predicted to cause substantial truncation of the encoded proteins. Therefore, loss of some, or all, functions of UBE2NL, MAGEE2 and GTPBP6 seems compatible with normal development and intellectual function.
