Ethylmalonic encephalopathy

Isobutyrylglycine C4 VAL Isobutyryl-CoA dehydrogenase deficiency Glutaric acidemia type II Ethylmalonic encephalopathy... 

Fig. 3.2.5 Profiles of acylcarnitines as their butyl esters in plasma (precursor of m/z 85 scan) of a normal control (a) and patients with various organic acidemias. Propionylcarnitine (C> m/z 274 peak 3) is the primary marker for both propionic acidemia (b) and methylmalonic acidemias (c). Note that an elevation of methylmalonylcarnitine (C4-UC m/z 374) is not typically found in patients with methylmalonic acidemias. In the three cases of ethylmalonic encephalopathy (d) analyzed in our laboratory, elevations of ,- (m/z 288 peak 4) and C5-acylcarnitine (m/z 302 peak 5) species were noted. Isolated C5-acylcarnitine elevations are encountered in patients with isovaleric acidemia (e), where it represents isovalerylcarnitine. Cs-Acylcarnitine is also elevated in patients with short/branched chain acyl-CoA dehydrogenase deficiency, where it represents 2-methylbutyrylcarnitine (see Fig. 3.2.4), and in patients treated with antibiotics that contain pivalic acid, where it represents pivaloylcarnitine [20, 59, 60]. Patients with /3-ketothio-lase deficiency (f) present with elevations of tiglylcarnitine (C5 i m/z 300 peak 6) and C5-OH acylcarnitine (m/z 318 peak 7). In most cases of 3-methylcrotonyl-CoA carboxylase deficiency (g) Cs-OH acylcarnitine is the only abnormal acylcarnitine species present. The differential diagnosis of C5-OH acylcarnitine elevations includes eight different conditions (Table 3.2.1). Also note that C5-OH acylcarnitine represents 3-hydroxy isovalerylcarnitine in 3-methylcrotonyl-CoA carboxylase deficiency (g), and 2-methyl 3-hydroxy butyrylcarnitine in / -ketothiolase deficiency...

Figure 55-12 Partial urine organic acid profiles (7-28 minute portion of a 33 minute run). A, Ethylmalonic encephalopathy.

EMA aciduria maybe associated with several other inherited and acquired conditions, including (1) glutaric acidemia type II (some cases are actually labeled to have ethylmalonic adipic aciduria),(2) disorders of the intramitochon-drial flavin adenine dinucleotide pathway, (3) mitochondrial respiratory chain disorders, and (4) ethylmalonic encephalopathy. Jamaican vomiting sickness (due to ingestion of unripe ackee fruit containing the poison hypoglycin A) and ifosfamide treatment represent two additional causes of ethylmalonic aciduria. 

Garcia-Silva MT, Ribes A, Campos Y, Garavaglia B, Arenas J. Syndrome of encephalopathy, petechiae, and ethylmalonic aciduria. Pediatr Neurol 1997 17 ... 

Tiranti V, D Adamo P, Briem E, Ferrari G, Mineri R, Lamantea E, et al. Ethylmalonic encephalopathy is caused by mutations in ETHEl, a gene encoding a mitochondrial matrix protein. Am J Hum Genet 2004 74 239-52... 

Yoon HR, Hahn SH, Ahn YM, Jang SH, Shin YJ, Lee EH, et al. Therapeutic trial in the first three Asian cases of ethylmalonic encephalopathy response to riboflavin. J Inherit Metab Dis 2001 24 870-3. 

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