Novel mutation in CNTNAP1 results in congenital hypomyelinating neuropathy.

INTRODUCTION: Congenital hypomyelinating neuropathy (CHN) is a rare congenital neuropathy that presents in the neonatal period and has been linked previously to mutations in several genes associated with myelination. A recent study has linked 4 homozygous frameshift mutations in the contactin-associated protein 1 (CNTNAP1) gene with this condition. METHODS: We report a neonate with CHN who was found to have absent sensory nerve and compound muscle action potentials and hypomyelination on nerve biopsy. RESULTS: On whole exome sequencing, we identified a novel CNTNAP1 homozygous missense mutation (p.Arg388Pro) in the proband, and both parents were carriers. Molecular modeling suggests that this variant disrupts a ß-strand to cause an unstable structure and likely significant changes in protein function. CONCLUSIONS: This report links a missense CNTNAP1 variant to the disease phenotype previously associated only with frameshift mutations. Muscle Nerve 55: 761-765, 2017.

Hereditary Sensory and Autonomic Neuropathy: A Case Series of Six Children.

Objectives: Hereditary sensory and autonomic neuropathy (HSAN) is a group of rare disorders affecting the sensory and autonomic neurons. Herein, we describe the clinical and genetic profile of six children with HSAN. Methods: Hospital records of six children diagnosed with HSAN over 7 years (2011-2018) were retrieved. Clinical features, electrophysiological studies, and genetic reports were collected from the case files. Results: The presenting clinical features in these six cases were developmental delay, recurrent febrile episodes, rhinitis, recurrent nonhealing ulcers, burns, self-mutilations, chronic osteomyelitis, and corneal ulcers. Electrophysiology studies showed predominant sensory axonal neuropathy. Autonomic features noted were recurrent fever, constipation, abdominal distension, hypertension, and vasomotor rhinitis. Genetic testing was done with next-generation sequencing in all six children. Causative genetic variants were identified in the NTRK1, PRDM12, DST gene, and a novel compound heterozygous variant in the FLVCR1 gene. The diagnosis of HSAN was delayed in most of our children due to variable presentation and lack of awareness among the treating paediatricians. Conclusions: Although the clinical presentation of HASN is highly variable, it is dominated by pain and temperature insensitivity and self-mutilation. Our report of six children with HSAN expands the existing knowledge on phenotype and genotype spectrum of HSAN.

Differentiating Familial Neuropathies from Guillain-Barré Syndrome.

Differentiating Guillain-Barré syndrome (GBS) from inherited neuropathies and other acquired peripheral neuropathies requires understanding the atypical presentations of GBS and its variant forms, as well as historical and physical features suggestive of inherited neuropathies. GBS is typically characterized by the acute onset of ascending flaccid paralysis, areflexia, and dysesthesia secondary to peripheral nerve fiber demyelination. The disorder usually arises following a benign gastrointestinal or respiratory illness, is monophasic, reaches a nadir with several weeks, and responds to immunomodulatory therapy. Inherited neuropathies with onset before adulthood, whose presentation may mimic Guillain-Barré syndrome, are reviewed.