A case of hyperinsulinism/hyperammonaemia syndrome with reduced carbamoyl-phosphate synthetase-1 activity in liver: a pitfall in enzymatic diagnosis for hyperammonaemia.
We report a patient who was first diagnosed as having congenital carbamoyl-phosphate synthetase-1 (CPS-1) deficiency on the basis of significantly low CPS-1 activity in the liver at 1 year of age. We then started therapy against hyperammonaemia with little effect and, at the age of 15 years, we analysed the GLUD1 gene and found a previously reported gain-of-function mutation in the gene, resulting in a change of her diagnosis to hyperinsulinism/hyperammonaemia (HI/HA) syndrome. This case demonstrates that low CPS-1 activity in liver, however significant it might be, does not always come from a primary CPS-1 deficiency and that we have to take into consideration the possibility of a secondary CPS-1 deficiency, such as HI/HA syndrome.
Ihara
K
K
Department of Pediatrics, Graduate School of Medical Sciences, Kyusyu University, Fukuoka, Japan. k-ihara@pediatr.med.kyushu-u.ac.jp
Miyako
K
K
Ishimura
M
M
Kuromaru
R
R
Wang
H-Y
HY
Yasuda
K
K
Hara
T
T
D000293:Adolescent; D000641:Ammonia / Q000378:metabolism; D002222:Carbamoyl-Phosphate Synthase (Ammonia) / Q000096:biosynthesis* / Q000172:deficiency*; D018076:DNA, Complementary / Q000378:metabolism; D003937:Diagnosis, Differential; D005091:Exons; D005260:Female; D005947:Glucose / Q000378:metabolism; D005969:Glutamate Dehydrogenase / Q000235:genetics; D006801:Humans; D022124:Hyperammonemia / Q000175:diagnosis*; D006946:Hyperinsulinism / Q000175:diagnosis*; D008099:Liver / Q000201:enzymology* / Q000378:metabolism; D008110:Liver Extracts / Q000378:metabolism; D008661:Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics; D009154:Mutation; D017422:Sequence Analysis, DNA; D013577:Syndrome; D013997:Time Factors
D018076:DNA, Complementary; D008110:Liver Extracts; D000641:Ammonia; D005969:Glutamate Dehydrogenase; D002222:Carbamoyl-Phosphate Synthase (Ammonia); D005947:Glucose