Hyperekplexia, microcephaly and simplified gyral pattern caused by novel ASNS mutations, case report.

Background: Asparagine synthetase deficiency (OMIM# 615574) is a very rare newly described neurometabolic disorder characterized by congenital microcephaly and severe global developmental delay, associated with intractable seizures or hyperekplexia. Brain MRI typically shows cerebral atrophy with simplified gyral pattern and delayed myelination. Only 12 cases have been described to date.

A novel syndrome of lethal familial hyperekplexia associated with brain malformation.

Background: Hyperekplexia (HPX) is a rare non-epileptic disorder manifesting immediately after birth with exaggerated persistent startle reaction to unexpected auditory, somatosensory and visual stimuli, and non-habituating generalized flexor spasm in response to tapping of the nasal bridge (glabellar tap) which forms its clinical hallmark. The course of the disease is usually benign with spontaneous amelioration with age. The disorder results from aberrant glycinergic neurotransmission, and several mutations were reported in the genes encoding glycine receptor (GlyR) α1 and β subunits, glycine transporter GlyT2 as well as two other proteins involved in glycinergic neurotransmission gephyrin and collybistin.