The First Turkish case with HIVEP2-related intellectual disability

Objective The genetic basis of mental motor retardation is still unknown.The human immunodeficiency virus type-1 regulatory binding protein 2(HIVEP2)gene is a new,closely associated with non-syndromic intellectual disability and plays a role in the regulation of many genes involved in the neurodevelopmental pathway.HIVEP2-related intellectual disability is a rare disorder.At least 11 individuals with the condition have been described in the medical literature. Methods Herein,we presented the first case with HIVEP2 mutation from Turkey. Results A seven-month-old male presented with hypotonia and recurrent ear infection.Physical and neurological examination revealed dysmorphic features such as hypertelorism,broad nasal root,low set ears,downslanting eyes,long filtrum,truncal hypotonia and limited speech with postnatal microcephaly.The genetic evaluation including karyotype analysis,microarray and test for Angelman syndrome were all normal.The brain magnetic resonance imaging and electroencephalography were also normal.When he reapplied after one and half year later,his motor delay became more prominent and his cognitive functions and speech were retarded. Since he was the first and only child in the family,WES analysis was performed. A new heterozygous HIVEP2 gene(NM_00673434.4) c.3G>A mutation was detected.Although his mother has the same heterozygous variant, we think that the clinic can be explained by incomplete penetration or variable expression patterns. Conclusion The HIVEP2 gene is a rare autosomal dominant cause of mental motor retardation and has been shown to cause global developmental delay, mild dysmorphic findings,hypotonia,behavioral problems,minimal structural brain abnormalities, and Angelman-like phenotypes Through this case,it is aimed to discuss intellectual disability without a clear genetic background by associating it with HIVEP2 mutation based on clinical findings.
Keywords: HIVEP2, motor mental retardation, intellectual disability