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The role of molecular testing and enzyme analysis in the management of hypomorphic citrullinemia
Author(s) -
Dimmock David P.,
Trapane Pamela,
Feigenbaum Annette,
Keegan Catherine E.,
Cederbaum Stephen,
Gibson James,
Gambello Michael J.,
Vaux Keith,
Ward Patricia,
Rice Gregory M.,
Wolff Jon A.,
O'Brien William E.,
Fang Ping
Publication year - 2008
Publication title -
american journal of medical genetics part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.064
H-Index - 112
eISSN - 1552-4833
pISSN - 1552-4825
DOI - 10.1002/ajmg.a.32527
Subject(s) - citrullinemia , argininosuccinate synthase , neurocognitive , citrulline , medicine , adverse effect , arginine , genetic testing , newborn screening , pregnancy , pediatrics , gastroenterology , biology , genetics , cognition , psychiatry , amino acid
Expanded newborn screening detects patients with modest elevations in citrulline; however it is currently unclear how to treat these patients and how to counsel their parents. In order to begin to address these issues, we compared the clinical, biochemical, and molecular features of 10 patients with mildly elevated citrulline levels. Three patients presented with clinical illness whereas seven came to attention as a result of expanded newborn screening. One patient presented during pregnancy and responded promptly to IV sodium phenylacetate/sodium benzoate and arginine therapy with no long‐term adverse effects on mother or fetus. Two children presented with neurocognitive dysfunction, one of these responded dramatically to dietary protein reduction. ASS enzyme activity was not deficient in all patients with biallelic mutations suggesting this test cannot exclude the ASS1 locus in patients with mildly elevated plasma citrulline. Conversely, all symptomatic patients who were tested had deficient activity. We describe four unreported mutations (p.Y291S, p.R272H, p.F72L, and p.L88I), as well as the common p.W179R mutation. In silico algorithms were inconsistent in predicting the pathogenicity of mutations. The cognitive benefit in one patient of protein restriction and the lack of adverse outcome in seven others restricted from birth, suggest a role for protein restriction and continued monitoring to prevent neurocognitive dysfunction. © 2008 Wiley‐Liss, Inc.