Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sepiapterin reductase (SR) catalyses the last step in the tetrahydrobiopterin biosynthesis pathway; it converts 6-pyruvoyl-tetrahydropterin (6-PTP) to BH(4) in an NADPH-dependent reaction. SR deficiency is a very rare autosomal recessive disorder with normal phenylalanine (Phe) concentration in blood and diagnostic abnormalities are detected in CSF. We present a 16-month-old girl with SR deficiency. From the newborn period she presented with an adaptation regulatory disorder. At the age of 3 months, abnormal eye movements with dystonic signs and at 4.5 months psychomotor retardation were noticed. Since that time axial hypotonia with limb spasticity (or rather delayed reflex development), gastro-oesophageal reflux and fatigue at the end of the day has been observed. Brain MRI was normal; EEG was without epileptiform discharges. Analysis of biogenic amine metabolites in CSF at the age of 16 months showed very low HVA and 5-HIAA concentrations. Analysis of CSF pterins revealed strongly elevated dihydrobiopterin (BH(2)), slightly elevated neopterin and elevated sepiapterin levels. Plasma and CSF amino acids concentrations were normal. A phenylalanine loading test showed increased Phe after 1 h, 2 h and 4 h and very high Phe/Tyr ratios. SR deficiency was confirmed in fibroblasts and a novel homozygous g.1330C>G (p.N127K) SPR mutation was identified. On L-dopa and then additionally 5-hydroxytryptophan, the girl showed slow but remarkable progress in motor and intellectual ability. Now, at the age of 3 years, she is able to sit; expressive speech is delayed (to 1 1/2 years), passive speech is well developed. Her visual-motor skills, eye-hand coordination and social development correspond to the age of 2 1/2 years.
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PMID:Sepiapterin reductase deficiency in a 2-year-old girl with incomplete response to treatment during short-term follow-up. 1913 Feb 91

Sepiapterin reductase (SR) deficiency is a rare autosomal recessively inherited error of tetrahydrobiopterin (BH4) biosynthesis, resulting in disturbed dopaminergic and serotonergic neurotransmission. The clinical phenotype is characterized by dopa-responsive movement disorders including muscular hypotonia, dystonia, and parkinsonism. Due to the rarity of the disease, the phenotype of SR deficiency is far from being completely understood. Here, we report a 7-year-old boy, who was referred for diagnostic evaluation of combined psychomotor retardation, spastic tetraplegia, extrapyramidal symptoms, and short stature. Due to discrepancy between motor status and mental condition, analyses of biogenic amines and pterins in CSF were performed, leading to the diagnosis of SR deficiency. The diagnosis was confirmed by a novel homozygous mutation c.530G>C; p.(Arg177Pro) in exon 2 of the SPR gene. Because of persistent short stature, systematic endocrinological investigations were initiated. Insufficient growth-hormone release in a severe hypoglycemic episode after overnight fasting confirmed growth-hormone deficiency as a cause of short stature. In addition, central hypothyroidism was present. A general hypothalamic affection could be excluded. Since dopamine is known to regulate growth-hormone excretion, IGF-1, IGF-BP3, and peripheral thyroid hormone levels were monitored under L-dopa/carbidopa supplementation. Both growth-hormone-dependent factors and thyroid function normalized under treatment. This is the first report describing growth-hormone deficiency and central hypothyroidism in SR deficiency. It extends the phenotypic spectrum of the disease and identifies dopamine depletion as cause for the endocrinological disturbances.
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PMID:Dopamine-Responsive Growth-Hormone Deficiency and Central Hypothyroidism in Sepiapterin Reductase Deficiency. 2600 22