Urine valine level above the normal range.

Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.

Forceful ejection of the contents of the stomach through the mouth by means of a series of involuntary spasmic contractions.

Abnormal feeling of sleepiness or difficulty staying awake.

Motor hyperactivity with excessive movement of muscles of the body as a whole.

Reduced strength of muscles.

Valinemia is an inborn error of metabolism characterized clinically by vomiting, feeding difficulties, hypotonia, and developmental delay, and biochemically by high concentrations of valine in serum and urine (Wada, 1965).

Valinemia is an inborn error of metabolism characterized clinically by vomiting, feeding difficulties, hypotonia, and developmental delay, and biochemically by high concentrations of valine in serum and urine (Wada, 1965).

Maple syrup urine disease (MSUD) is categorized as classic (severe), intermediate, or intermittent. Neonates with classic MSUD are born asymptomatic but without treatment follow a predictable course: 12–24 hours. Elevated concentrations of branched-chain amino acids (BCAAs; leucine, isoleucine, and valine) and alloisoleucine, as well as a generalized disturbance of amino acid concentration ratios, are present in blood and the maple syrup odor can be detected in cerumen; Two to three days. Early and nonspecific signs of metabolic intoxication (i.e., irritability, hypersomnolence, anorexia) are accompanied by the presence of branched-chain alpha-ketoacids, acetoacetate, and beta-hydroxybutyrate in urine; Four to six days. Worsening encephalopathy manifests as lethargy, apnea, opisthotonos, and reflexive "fencing" or "bicycling" movements as the sweet maple syrup odor becomes apparent in urine; Seven to ten days. Severe intoxication culminates in critical cerebral edema, coma, and central respiratory failure. Individuals with intermediate MSUD have partial branched-chain alpha-ketoacid dehydrogenase deficiency that manifests only intermittently or responds to dietary thiamine therapy; these individuals can experience severe metabolic intoxication and encephalopathy in the face of sufficient catabolic stress. In the era of newborn screening (NBS), the prompt initiation of treatment of asymptomatic infants detected by NBS means that most individuals who would have developed neonatal manifestations of MSUD remain asymptomatic with continued treatment adherence.

Myopathy with extrapyramidal signs is an autosomal recessive disorder characterized by early childhood onset of proximal muscle weakness and learning disabilities. While the muscle weakness is static, most patients develop progressive extrapyramidal signs that may become disabling (summary by Logan et al., 2014). Brain MRI in 1 patient showed congenital malformations, including polymicrogyria and cerebellar dysplasia (Wilton et al., 2020).

Hypervalinemia and hyperleucine-isoleucinemia (HVLI) is a branched-chain amino acid metabolic disorder characterized by highly elevated plasma valine and leucine concentrations. The patient presented in adulthood with headache and mild memory impairment, and had abnormal symmetric white matter signals on brain MRI (Wang et al., 2015).

Hypermetabolism due to uncoupled mitochondrial oxidative phosphorylation-2 (HUMOP2) is characterized by failure to thrive apparent in infancy despite adequate caloric intake. Affected individuals show normal thyroid function, hyperphagia, tachypnea, increased basal temperature, and increased sweating. Biochemical studies demonstrate increased mitochondrial oxygen consumption with inefficient production of ATP in the final steps of oxidative phosphorylation due to an uncoupling defect (Ganetzky et al., 2022). Genetic Heterogeneity of Hypermetabolism due to Uncoupled Mitochondrial Oxidative Phosphorylation See also HUMOP1 (238800).