Disorders of branched-chain amino-acid metabolism and fatty-acid metabolism (E71)

The ICD-10 code E71 covers a group of rare metabolic disorders affecting the processing of branched-chain amino acids and fatty acids. These disorders include well-known conditions like maple syrup urine disease and various defects in fatty-acid oxidation and carnitine metabolism.

This section is used to classify inherited metabolic abnormalities such as maple syrup urine disease (E71.0), which is also referred by synonyms including mild, classical, and thiamin-responsive forms. It also includes branched-chain organic acidurias like isovaleric acidemia (E71.110) and several types of 3-methylglutaconic aciduria, disorders of propionate metabolism such as methylmalonic acidemia (E71.120) and propionic acidemia (E71.121). Fatty-acid metabolism disorders are classified here, including fatty-acid oxidation deficiencies like medium chain acyl CoA dehydrogenase deficiency (E71.311). The section further covers carnitine metabolism issues, including primary carnitine deficiency (E71.41) and secondary forms. Peroxisomal disorders, such as Zellweger syndrome (E71.510) and X-linked adrenoleukodystrophy variants, also fall under E71. Specialized terms like acyl-CoA dehydrogenase deficiency or carnitine palmitoyltransferase deficiency appear here, guiding coders to the precise ICD-10 code for specific metabolic defects.

Clinical Terms

The following clinical terms provide additional context, helping users better understand the clinical background and common associations for each diagnosis listed in this section. Including related terms alongside ICD-10-CM codes supports coders, billers, and healthcare professionals in improving accuracy, enhancing documentation, and facilitating research or patient education.

Adrenoleukodystrophy

An X-linked recessive disorder characterized by the accumulation of saturated very long chain fatty acids in the LYSOSOMES of ADRENAL CORTEX and the white matter of CENTRAL NERVOUS SYSTEM. This disease occurs almost exclusively in the males. Clinical features include the childhood onset of ATAXIA; NEUROBEHAVIORAL MANIFESTATIONS; HYPERPIGMENTATION; ADRENAL INSUFFICIENCY; SEIZURES; MUSCLE SPASTICITY; and DEMENTIA. The slowly progressive adult form is called adrenomyeloneuropathy. The defective gene ABCD1 is located at Xq28, and encodes the adrenoleukodystrophy protein (ATP-BINDING CASSETTE TRANSPORTERS).

ATP Binding Cassette Transporter, Subfamily D, Member 1

ATP-binding cassette transporter that functions in the import of long chain (13-21 carbons) and very long chain fatty acids (> 22 carbons), or their acyl-CoA-derivatives, into PEROXISOMES. Mutations in the ABCD1 gene are associated with the X-linked form of ADRENOLEUKODYSTROPHY.

Homocystinuria

Autosomal recessive inborn error of methionine metabolism usually caused by a deficiency of CYSTATHIONINE BETA-SYNTHASE and associated with elevations of homocysteine in plasma and urine. Clinical features include a tall slender habitus, SCOLIOSIS, arachnodactyly, MUSCLE WEAKNESS, genu varus, thin blond hair, malar flush, lens dislocations, an increased incidence of MENTAL RETARDATION, and a tendency to develop fibrosis of arteries, frequently complicated by CEREBROVASCULAR ACCIDENTS and MYOCARDIAL INFARCTION. (From Adams et al., Principles of Neurology, 6th ed, p979)

Maple Syrup Urine Disease

An autosomal recessive inherited disorder with multiple forms of phenotypic expression, caused by a defect in the oxidative decarboxylation of branched-chain amino acids (AMINO ACIDS, BRANCHED-CHAIN). These metabolites accumulate in body fluids and render a maple syrup odor. The disease is divided into classic, intermediate, intermittent, and thiamine responsive subtypes. The classic form presents in the first week of life with ketoacidosis, hypoglycemia, emesis, neonatal seizures, and hypertonia. The intermediate and intermittent forms present in childhood or later with acute episodes of ataxia and vomiting. (From Adams et al., Principles of Neurology, 6th ed, p936)

Peroxisomal Disorders

A heterogeneous group of inherited metabolic disorders marked by absent or dysfunctional PEROXISOMES. Peroxisomal enzymatic abnormalities may be single or multiple. Biosynthetic peroxisomal pathways are compromised, including the ability to synthesize ether lipids and to oxidize long-chain fatty acid precursors. Diseases in this category include ZELLWEGER SYNDROME; INFANTILE REFSUM DISEASE; rhizomelic chondrodysplasia (CHONDRODYSPLASIA PUNCTATA, RHIZOMELIC); hyperpipecolic acidemia; neonatal adrenoleukodystrophy; and ADRENOLEUKODYSTROPHY (X-linked). Neurologic dysfunction is a prominent feature of most peroxisomal disorders.

Propionic Acidemia

Autosomal recessive metabolic disorder caused by mutations in PROPIONYL-COA CARBOXYLASE genes that result in dysfunction of branch chain amino acids and of the metabolism of certain fatty acids. Neonatal clinical onset is characterized by severe metabolic acidemia accompanied by hyperammonemia, HYPERGLYCEMIA, lethargy, vomiting, HYPOTONIA; and HEPATOMEGALY. Survivors of the neonatal onset propionic acidemia often show developmental retardation, and intolerance to dietary proteins. Late-onset form of the disease shows mild mental and/or developmental retardation, sometimes without metabolic acidemia.

Zellweger Syndrome

An autosomal recessive disorder due to defects in PEROXISOME biogenesis which involves more than 13 genes encoding peroxin proteins of the peroxisomal membrane and matrix. Zellweger syndrome is typically seen in the neonatal period with features such as dysmorphic skull; MUSCLE HYPOTONIA; SENSORINEURAL HEARING LOSS; visual compromise; SEIZURES; progressive degeneration of the KIDNEYS and the LIVER. Zellweger-like syndrome refers to phenotypes resembling the neonatal Zellweger syndrome but seen in children or adults with apparently intact peroxisome biogenesis.