Workup
Laboratory Studies
See the list below:
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Determine proteolytic activity in patients with intestinal enterokinase deficiency before and after activation with exogenous enterokinase in a duodenal juice sample collected during a pancreozymin-secretin test.
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Perform column chromatography of duodenal juice before and after activation with exogenous enterokinase.
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Trypsin activity in duodenal fluid is low or absent; activity returns after the addition of enterokinase. Lipase and amylase activity levels are within reference ranges.
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Assay enterokinase activity in duodenal juice and intestinal mucosa.
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Enterokinase activity in duodenal fluid and mucosal homogenate is less than 10% of age-matched control values.
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The human proenteropeptidase complementary DNA (cDNA) has been cloned, and the gene has been mapped. [8]
Media Gallery
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Position of mutations (red arrows), in relation to proenteropeptidase exon organization, domains, and amino acid residues forming the active site of the serine protease domain (H825, D876, and S971 [blue arrows]). All 4 mutations identified are null mutations that predict the absence of a correctly formed active site. The previously described modular structure of proenteropeptidease domains, based on primary-structure comparison, correlates with exon boundaries. SA = signal/anchor sequence; LDLR = LDL receptorlike domain; Muc = Mucin-domain; Meprin = Meprinlike domain; C1r/s = Complement component C1rlike domain; MSCR = Macrophage scavenger receptorlike domain. Adapted from American Journal of Human Genetics.
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