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Hereditary sensory and autonomic neuropathy type IV is an autosomal recessive disorder characterized by severe mental retardation and self-mutilation-related complications. Recently, we investigated a 16-year-old Korean boy with normal intelligence. He had preserved pain sensation but was suspected of having hereditary sensory and autonomic neuropathy type IV because of the recurrent bone fractures and painless joint destruction in the absence of any predisposing medical conditions. Genetic analysis of the NTRK1 gene revealed compound heterozygous mutations including c.851-33T>A and c.2303C>T (p.Pro768Leu) in the NTRK1 gene. The p.Pro768Leu mutation has been identified in 2 Japanese patients with a mild phenotype. Therefore, although it is rare, hereditary sensory and autonomic neuropathy type IV should be considered in patients with recurrent bone fractures and painless joint destruction who do not have any predisposing conditions even when they do not have typical clinical features such as mental retardation or pain insensitivity. [ABSTRACT FROM PUBLISHER]

Hyperekplexia is a rare inherited neurologic disorder that is characterized by hypertonia and an exaggerated startle response to sudden external stimuli. Until now, 5 genes are known to be associated with hyperekplexia: GLRA1, SLC6A5, GLRB, GPHN, and ARHGEF9. In this report, we performed a clinical and genetic analysis of 4 Korean children with hyperekplexia. Two patients had typical clinical manifestations of hyperekplexia that initially were misdiagnosed as epilepsy. Direct sequencing of the GLRB and GLRA1 genes revealed 2 novel mutations, GLRB c.298-1G>A and c.1028C>T (p.S343F), in patient 1 and 1 novel mutation, GLRA1 c.895C>T (p.R299X), in patient 2. The other 2 familial cases, patients 3 and 4, exhibited startle responses, which appeared at the age of 1 year, and had global developmental delay. Those patients showed negative results for the 5 genes. [ABSTRACT FROM AUTHOR]

Pompe disease is an autosomal recessive disorder caused by lysosomal acid α-glucosidase deficiency. Infantile-onset Pompe disease presents with cardiomyopathy and hypotonia, leading to premature death. This article describes 7 infantile Pompe disease cases and provides their molecular bases and clinical outcomes after enzyme replacement therapy for the first time in Korea. Molecular genetic analyses revealed the presence of 9 different mutations, including 5 novel mutations (c.2171C>A, c.2774C>T, c.1582_3de12, c.1261_1263Tms, and c.1322_1326+9de114). The most common mutation in these 7 patients was c.1316T>A (28%). Four patients received intravenous recombinant human acid α-glucosidase therapy for 2 years, on average, without significant side effects during the treatment course. They all exhibited increased muscle power, with considerable improvement in cardiac function. Pompe disease is heterogeneous regarding both clinical features and molecular characteristics. Early identification of Pompe disease is very important, considering that enzyme replacement therapy is a safe and effective treatment for early-onset patients. [ABSTRACT FROM AUTHOR]