Burn-McKeown syndrome Overview Burn-McKeown syndrome is a rare, congenital genetic disorder characterized by nasal passage blockages, distinctive facial features, hearing loss, and heart or growth abnormalities, while generally leaving intelligence unaffected Symptoms • Nasal Passage Abnormalities: • Bilateral choanal stenosis (narrowing) or bilateral choanal atresia (complete blockage of the nasal passages), which can lead to life-threatening breathing and respiratory distress issues in newborns if not surgically repaired. • Craniofacial (Facial) Features: • Short palpebral fissures: Narrow openings of the eyelids, sometimes accompanied by downslanting. • Coloboma: A gap or defect in the lower eyelids, often with eyelashes present medial to the defect. • Hypertelorism: Widely spaced eyes. • Prominent nasal bridge: A high or prominent bridge of the nose. • Philtrum abnormalities: A short space between the nose and the upper lip. • Mouth and lips: A small opening of the mou...
Tetrahydrobiopterin Deficiency Overview Tetrahydrobiopterin (BH4) deficiencies is a general term for a group of disorders characterized by abnormalities in the creation (biosynthesis) or regeneration of tetrahydrobiopterin, a naturally occurring compound that acts as a cofactor. A cofactor is a non-protein substance in the body that enhances or is necessary for the proper function of certain enzymes. When tetrahydrobiopterin is deficient, the chemical balance within the body is upset. In most of these disorders, there are abnormally high levels of the amino acid phenylalanine (hyperphenylalaninemia). Amino acids such as phenylalanine are chemical building blocks of proteins and are essential for proper growth and development. Most of these disorders also cause abnormally low levels of neurotransmitters. Neurotransmitters are chemicals that modify, amplify or transmit nerve impulses from one nerve cell to another, enabling nerve cells to communicate. These chemical imbalances can ultima...