Steroid 21-hydroxylase deficiency is the most prevalent form of congenital adrenal hyperplasia (CAH), accounting for approximately 95% of cases. With the advent of newborn screening and hormone replacement therapy, most children with CAH survive into adulthood. Adolescents and adults with CAH experience a number of complications, including short stature, obesity, infertility, tumor, osteoporosis, and reduced quality of life. Transition from...

Phelan-McDermid syndrome is a rare genetic disorder caused by the terminal or interstitial deletion of the chromosome 22q13.3. Patients with this syndrome usually have global developmental delay, hypotonia, and speech delays. Several putative genes such as the SHANK3, RAB, RABL2B, and IB2 are responsible for the neurological features. This study describes the clinical features and outcomes of Korean patients with...

Mucopolysaccharidosis type III (MPS III) is a rare genetic disorder caused by lysosomal storage of heparan sulfate. MPS IIIB results from a deficiency in the enzyme alpha-N-acetyl-D-glucosaminidase (NAGLU). Affected patients begin showing behavioral changes, progressive profound mental retardation, and severe disability from the age of 2 to 6 years. We report a patient with MPS IIIB with a long-term follow-up...

Cerebral cavernous malformation (CCM) is a vascular malformation characterized by abnormally enlarged capillary cavities without any intervening neural tissue. We report 2 cases of familial CCMs diagnosed with the CCM1 mutation by using a genetic assay. A 5-year-old boy presented with headache, vomiting, and seizure-like movements. Brain magnetic resonance imaging (MRI) revealed multiple CCM lesions in the cerebral hemispheres. Subsequent...

Permanent neonatal diabetes mellitus refers to diabetes that occurs before the age of 6 months and persists through life. It is a rare disorder affecting one in 0.2-0.5 million live births. Mutations in the gene KCNJ11, encoding the subunit Kir6.2, and ABCC8, encoding SUR1 of the ATP-sensitive potassium (K_ATP) channel, are the most common causes of permanent neonatal diabetes mellitus....

Isovaleric aciduria (IVA) is caused by an autosomal recessive deficiency of isovaleryl-CoA dehydrogenase (IVD). IVA presents either in the neonatal period as an acute episode of fulminant metabolic acidosis, which may lead to coma or death, or later as a "chronic intermittent form" that is associated with developmental delays, with or without recurrent acidotic episodes during periods of stress, such...

Chronic pancreatitis is a progressive inflammatory disease resulting from repeated episodes of acute pancreatitis that impair exocrine function and eventually produce endocrine insufficiency. Some causes of chronic pancreatitis appear to be associated with alterations in the serine-protease inhibitor, Kazal type 1 (SPINK1), cationic trypsinogen (PRSS1), and cystic fibrosis-transmembrane conductance regulator (CFTR) genes, or with structural disorders in the pancreaticobiliary ductal...

X-linked recessive myotubular myopathy (XLMTM) is a severe congenital muscle disorder caused by mutations in the MTM1 gene and characterized by severe hypotonia and generalized muscle weakness in affected males. It is generally a fatal disorder during the neonatal period and early infancy. The diagnosis is based on typical histopathological findings on muscle biopsy, combined with suggestive clinical features. We...

Pelizaeus-Merzbacher disease (PMD) is a rare, X-linked recessive disorder characterized by dysmyelination in the central nervous system. PMD results from deletion, mutation, or duplication of the proteolipid protein gene (PLP1) located at Xq22, leading to the failure of axon myelination by oligodendrocytes in the central nervous system. PMD may be suspected when there are clinical manifestations such as nystagmus, developmental...