TRIGGERING HEREDITARY NEUROPATHY WITH LIABILITY TO PRESSURE PALSIES; A report has been received from a literature article concerning a 19 years old male patient.    The authors reported the case of a 19-year-old previously healthy man, who presented with 2 weeks of numbness, tingling and weakness in both upper and lower extremities. He had received influenza vaccine ((influenza virus vaccine live) (unknown manufacturer, route and formulation) 2 weeks before the onset of symptoms and did 20 push-ups (part of his physical fitness exam) the night before his symptoms started.     On physical examination, he had high feet arches and bilateral scapular winging. Medical history was not significant. He denied previous episodes of wrist drop, foot drop or numbness, and tingling. His father had arterial hypertension and high feet arches but no weakness. He did not take any prescription medicines and denied tobacco, alcohol, and illicit drug use. He had been in the job for 9 months and exercised regularly, as part of his training.    Neurological examination showed Agency strength of 3/5 in intrinsic hand muscles and finger extensors (other muscles including lower extremities were 5/5); decreased vibration and pinprick at toes and hands, absent deep tendon reflexes and a negative Babinski sign.  Nerve conduction study (NCS) showed absent median sensory nerve action potential (SNAP), small ulnar and radial SNAPs with prolonged peak latencies, and sural SNAP amplitudes of 7 mV. Bilateral median and ulnar motor NCS showed prolonged onset latencies, small compound motor action potential (CMAP) amplitudes, slow conduction velocities, and prolonged F-waves. Peroneal and tibial motor NCS showed normal onset latencies, CMAP amplitudes, and slightly slow conduction velocities (39 m/s). Electromyography showed active denervation in abductor pollicis brevis and first dorsal interosseous.  Cerebrospinal fluid showed slightly elevated protein (48 mg/dL) and 3 white blood cells.    Diagnosis of Guillain-Barre syndrome was made based on acute onset, sural sparing on NCS and prolonged latencies and F-waves. Intravenous immunoglobulin 2 g/kg divided into 4 doses was administered with minimal clinical improvement. Although he had no neurological history, the symptom onset after vigorous exercise, the presence of high foot arches and scapular winging led us to suspect HNPP, and genetic testing was ordered. He was found to have PMP22 gene deletion, consistent with diagnosis of hereditary neuropathy with liability to pressure palsies (HNPP) (preferred term: hereditary neuropathy with liability to pressure palsies).    At 2 months follow-up, scapular winging had resolved, and median and ulnar CMAP amplitudes have returned to normal, but there was electrophysiological evidence of median neuropathy at the wrist and ulnar neuropathy at the elbow. Sural SNAP amplitude was 6 mV.    The event was considered serious (important medical event).    Laboratory values and diagnostic test details are available.    The authors highlighted: "The possible role of the influenza vaccine in triggering HNPP symptoms, in our case, deserves to be mentioned. Although HNPP patients can develop symptoms with only exercise as a trigger even after being enrolled in the program, we postulate that, in our previously asymptomatic patient, the influenza immunization triggered a mild transient autoimmune reaction that coupled with excessive exercise led to his acute neuropathy."    Major correction on 04-Feb-2021: Seriousness updated from non serious to serious (important medical event). Route and formulation added. Narrative updated.    Minor correction on 05-Feb-2021: Company clinical comment updated. Narrative updated.; Sender's Comments: This case concerns a 19 year old male vaccinee with reported event of Hereditary neuropathy with liability to pressure palsies in association with Q/LAIV (Quadrivalent/ Live attenuated influenza vaccine). The event occurred after 2 weeks post vaccine. It was mentioned in the case, the patient was found to have PMP22 gene deletion, consistent with diagnosis of hereditary neuropathy with liability to pressure palsies . Due to limited information on relevant medical history, family history, risk factors, treatment given, the evaluation did not find evidence to suggest a reasonable possibility of a causal relationship between event and suspect drug.