Serum pancreatic enzymes define the pancreatic phenotype in patients with Shwachman-Diamond syndrome.
OBJECTIVE
To evaluate the role of serum enzymes for defining the pancreatic phenotype in Shwachman-Diamond syndrome (SDS), an inherited multisystem condition.


METHODS
Serum pancreatic trypsinogen and isoamylase were measured in 164 patients known or presumed to have SDS. The diagnosis was confirmed in 90 patients. Among 74 unconfirmed cases, 35 ("probable SDS") had hematologic dysfunction but lacked documented pancreatic dysfunction, whereas 39 patients ("improbable SDS") lacked both documented pancreatic and hematologic dysfunction. Classification and regression tree (CART) analysis was performed in 90 patients with SDS and 134 control patients to establish a rule for defining the pancreatic phenotype of SDS; the rule was then applied to the patients with unconfirmed diagnosis.


RESULTS
In the control patients, serum trypsinogen showed little variation with age, whereas serum isoamylase values rose from birth on, attaining adult values by 3 years. For patients with SDS, serum trypsinogen values were low in young patients and tended to increase with age, whereas serum isoamylase values remained low at all ages. The CART rule combined results from both enzymes and classified the pancreatic phenotype in all but one SDS patient, who was <3 years of age. Excluding patients <3 years of age, CART identified the pancreatic phenotype in 82% and 7% of the "probable SDS" and "improbable SDS" cases, respectively.


CONCLUSIONS
Serum pancreatic enzymes are useful for determining the pancreatic phenotype and confirming the diagnosis of SDS.
Department of Pediatrics, University of Toronto, Ontario, Canada.
Wan F
WF
Ip
Annie
A
Dupuis
Lynda
L
Ellis
Satti
S
Beharry
Jodi
J
Morrison
Michael O
MO
Stormon
Mary
M
Corey
Johanna M
JM
Rommens
Peter R
PR
Durie
D000015:Abnormalities, Multiple / Q000097:blood / Q000201:enzymology* / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D002869:Chromosome Aberrations; D002897:Chromosomes, Human, Pair 7 / Q000201:enzymology* / Q000235:genetics*; D019411:Clinical Laboratory Techniques; D010188:Exocrine Pancreatic Insufficiency / Q000097:blood / Q000201:enzymology* / Q000235:genetics*; D005260:Female; D006402:Hematologic Diseases / Q000097:blood / Q000175:diagnosis / Q000201:enzymology; D006801:Humans; D007223:Infant; D007229:Infant Welfare; D020300:Intracranial Hemorrhages / Q000097:blood / Q000201:enzymology / Q000401:mortality; D007517:Isoamylase / Q000097:blood* / Q000235:genetics*; D008297:Male; D010179:Pancreas / Q000098:blood supply* / Q000201:enzymology*; D010641:Phenotype; D012189:Retrospective Studies; D013577:Syndrome; D014362:Trypsinogen / Q000097:blood* / Q000235:genetics*
D015415:Biomarkers; D014362:Trypsinogen; D007517:Isoamylase