title: A novel syndrome of lethal familial hyperekplexia associated with brain malformation.
abstract: 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.
  
  
  METHODS
  The phenotype of six newborns, belonging to Saudi Arabian kindred with close consanguineous marriages, who presented with hyperekplexia associated with severe brain malformation, is described. DNA samples were available from two patients, and homozygosity scan to determine overlap with known hyperkplexia genes was performed.
  
  
  RESULTS
  The kindred consisted of two brothers married to their cousin sisters, each with three affected children who presented antenatally with excessive fetal movements. Postnatally, they were found to have microcephaly, severe hyperekplexia and gross brain malformation characterized by severe simplified gyral pattern and cerebellar underdevelopment. The EEG was normal and they responded to clonazepam. All of the six patients died within six weeks. Laboratory investigations, including metabolic screen, were unremarkable. None of the known hyperkplexia genes were present within the overlapping regions of homozygosity between the two patients for whom DNA samples were available.
  
  
  CONCLUSIONS
  We present these cases as a novel syndrome of lethal familial autosomal recessive hyperekplexia associated with microcephaly and severe brain malformation.
authors.affiliation: Division of Pediatric Neurology, Department of Pediatrics (39), College of Medicine, King Saud University, P. O. Box 2925, Riyadh, 11461, Saudi Arabia.
authors.forename: Mohammed Zein
authors.initials: MZ
authors.lastname: Seidahmed
authors.forename: Mustafa A
authors.initials: MA
authors.lastname: Salih
authors.forename: Omer B
authors.initials: OB
authors.lastname: Abdulbasit
authors.forename: Meeralebbae
authors.initials: M
authors.lastname: Shaheed
authors.forename: Khalid
authors.initials: K
authors.lastname: Al Hussein
authors.forename: Abeer M
authors.initials: AM
authors.lastname: Miqdad
authors.forename: Abdullah K
authors.initials: AK
authors.lastname: Al Rasheed
authors.forename: Anas M
authors.initials: AM
authors.lastname: Alazami
authors.forename: Ibrahim A
authors.initials: IA
authors.lastname: Alorainy
authors.forename: Fowzan S
authors.initials: FS
authors.lastname: Alkuraya
mesh_terms: D003937:Diagnosis, Differential; D004827:Epilepsy / Q000175:diagnosis*; D017809:Fatal Outcome; D005260:Female; D040181:Genetic Diseases, X-Linked / Q000175:diagnosis*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D054220:Malformations of Cortical Development / Q000175:diagnosis*; D012021:Reflex, Abnormal; D013577:Syndrome