| Entity | Causal gene/defect | Key biomarkers | Core clinical features | Notes on diagnosis/screening | Key citations |
|---|---|---|---|---|---|
| Human NADK2-related secondary DECR deficiency | Autosomal recessive NADK2 loss causing mitochondrial NADP(H) deficiency with secondary impairment of NADPH-dependent DECR activity; DECR1 coding mutations were excluded in the reported modern cases | Elevated C10:2 (decadienoyl)carnitine; hyperlysinemia in plasma/CSF/urine; elevated lactate; low free carnitine; abnormal urinary organic acids; residual fibroblast DECR activity ~10% | Early infancy onset; failure to thrive, developmental delay, hypotonia, progressive encephalopathy, movement disorder/choreoathetosis-dystonia, visual loss/cortical blindness, epilepsy, renal tubular acidosis; death in childhood in severe cases | Diagnosis integrated acylcarnitines, amino acids, fibroblast enzyme assay, and exome sequencing; mild newborn-screen C10:2 elevation may occur but is not fully sensitive/specific; authors suggested lysine might improve screening specificity | (pqac-00000000, pqac-00000001, pqac-00000003, pqac-00000008, pqac-00000009, pqac-00000011) |
| Historical 1990 DECR deficiency case | Biochemical mitochondrial 2,4-dienoyl-CoA reductase deficiency reported before modern molecular diagnosis; residual DECR activity 17% in muscle and 40% in liver; later literature indicates DECR1 mutations were not demonstrated in similar cases | Elevated plasma C10:2-carnitine; hyperlysinemia | Failure to thrive, persistent hypotonia, microcephaly; death at 4 months | Landmark historical case establishing the phenotype/biochemical signature; no definitive molecular cause reported in the available evidence | (pqac-00000004, pqac-00000010) |
| Decr1 knockout mouse | Targeted Decr1/Decr disruption causing primary loss of mitochondrial 2,4-dienoyl-CoA reductase and defective PUFA β-oxidation | Increased serum decadienoylcarnitine (C10:2); urinary unsaturated dicarboxylic acids; hepatic steatosis with unsaturated fatty acid accumulation; hypoglycemia during fasting/stress | Usually compensated at baseline, but severe fasting/stress intolerance, profound hypoglycemia, impaired cold tolerance/thermogenesis, fatty liver; ketogenesis preserved | Strong mechanistic model for interpreting human C10:2 biomarker and PUFA β-oxidation block; supports causal role of DECR in metabolic adaptation rather than proving human DECR1-mutant cases | (pqac-00000007, pqac-00000005, pqac-00000014) |


*Table: This table contrasts the historical human DECR phenotype, modern NADK2-related secondary DECR deficiency, and the Decr1 knockout mouse model. It highlights the key biomarker pattern, phenotype, and diagnostic implications useful for rare disease knowledge-base curation.*