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Misleading diagnosis of partial N‐acetylglutamate synthase deficiency based on enzyme measurement corrected by mutation analysis
Author(s) -
Heckmann M.,
Wermuth B.,
Häberle J.,
Koch H. G.,
Gortner L.,
Kreuder J. G.
Publication year - 2005
Publication title -
acta pædiatrica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 115
eISSN - 1651-2227
pISSN - 0803-5253
DOI - 10.1111/j.1651-2227.2005.tb01799.x
Subject(s) - hyperammonemia , urea cycle , medicine , endocrinology , compound heterozygosity , phenylbutyrate , mutation testing , mutation , sibling , gastroenterology , arginine , biochemistry , biology , gene , psychology , developmental psychology , amino acid
Abstract N‐acetylglutamate synthase (NAGS) deficiency is a rare urea cycle disorder. Most of the patients present in the early neonatal period with severe hyperammonaemia and marked neurological impairment. We report on a Turkish family with an index patient, who died due to hyperammonemia, and another three siblings, who received a prophylactic treatment consisting of arginine hydrochloride, sodium benzoate and phenylbutyrate directly after birth. Enzyme measurement in a liver biopsy suggested a diagnosis of partial NAGS deficiency in all three siblings. Thereafter, N‐carbamylglutamate was added to the treatment. None of the patients developed hyperammonaemia. After the human NAGS gene was identified, mutation analysis revealed that the consanguineous parents and two siblings were heterozygous for a private mutation (W484R), whereas the wild‐type gene was found in the eldest sibling. Therapy was stopped without any deterioration of urea cycle function. Conclusion: Diagnosis of partial NAGS deficiency based on enzyme measurement may be misleading and should be completed by mutation analysis.