title: Sitosterolemia Presenting as Pseudohomozygous Familial Hypercholesterolemia.
abstract: A young girl, age 8.5 years, presented with profound hypercholesterolemia and early xanthomatosis, suggesting homozygous familial (or type II) hypercholesterolemia. The patient's low density lipoprotein (LDL) receptor function and parental lipoprotein profiles were determined to be normal, prompting revision of the initial diagnosis to pseudohomozygous familial hypercholesterolemia. When she subsequently presented with giant platelets, the case was presented to colleagues on an electronic mailing list. It was recommended that plasma and sterol analysis be performed, which led to a diagnosis of sitosterolemia. The presentation of profound hypercholesterolomia in childhood that ultimately is not attributed as due to homozygous or compound heterozygous defects in the LDL receptor gene has been termed pseudohomozygous familial (or type II) hypercholesterolemia (PHT2HC). Patients diagnosed with PHT2HC subsequently confirmed to have sitosterolemia have been previously reported only rarely. The challenge of achieving accurate specific diagnosis and appropriate workup for these conditions in children is discussed in the context of this rare case and review of the historical literature concerning these conditions.
authors.affiliation: Kinder und Jugendart Praxis, Pfleggasse 31, D-94469 Deggendorf, Germany cjrenner@well.com.
authors.forename: Christian
authors.initials: C
authors.lastname: Renner
authors.affiliation: Department of Medicine, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: William E
authors.initials: WE
authors.lastname: Connor
authors.affiliation: Department of Pediatrics and Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon, USA Marshfield Clinic Research Foundation, Marshfield, USA.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Steiner
mesh_terms: D001792:Blood Platelets / Q000166:cytology; D002648:Child; D003937:Diagnosis, Differential; D005260:Female; D006720:Homozygote; D006801:Humans; D006937:Hypercholesterolemia / Q000175:diagnosis* / Q000235:genetics*; D006938:Hyperlipoproteinemia Type II / Q000175:diagnosis* / Q000235:genetics*; D007410:Intestinal Diseases / Q000175:diagnosis* / Q000235:genetics*; D008052:Lipid Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics*; D010840:Phytosterols / Q000009:adverse effects* / Q000235:genetics; D011973:Receptors, LDL / Q000235:genetics; D013261:Sterols / Q000097:blood; D016896:Treatment Outcome; D014973:Xanthomatosis / Q000150:complications / Q000235:genetics
chemical_list: C573412:LDLR protein, human; D010840:Phytosterols; D011973:Receptors, LDL; D013261:Sterols
keywords: Familial hypercholesterolemia; Pseudohomozygous type II hypercholesterolemia; Sitosterolemia