title: Are MPS II heterozygotes actually asymptomatic? A study based on clinical and biochemical data, X-inactivation analysis and imaging evaluations.
abstract: For some X-linked disorders the expressivity and penetrance in females are almost similar to those ones found in males. For mucopolysaccharidosis type II (MPS II), there are no studies in the literature trying to identify subtle signs and symptoms of this disease in heterozygotes. The objective of this study was to compare heterozygotes and non-heterozygotes for MPS II, in order to test the hypothesis that heterozygotes may present subtle manifestations of the disease. In this observational and transversal study we collected data on 40 Brazilian women with a positive familial history for MPS II that included clinical and physical exam, karyotype, pattern of X-inactivation, iduronate-2-sulfatase (IDS) activity in leukocytes and plasma, urinary glycosaminoglycans levels, computerized tomography scans (CT) of abdomen and spine, and brain magnetic resonance imaging. The Results showed the following: According to DNA analysis, 22 women were classified as heterozygote and 18 as non-heterozygotes. We did not find any abnormality on physical examination, karyotype, or spine CT. Also the pattern of X-inactivation was not different between the groups. Applying the Bonferroni's correction, both groups were found to differ only in relation to IDS activity in plasma and in leukocyte, which were lower in heterozygotes. In our investigation we did not find any evidence of subtle clinical manifestations of MPS II in heterozygotes. Our findings suggest there is no relation between the absence of clinical signs in these women and the occurrence of a favorable skewing pattern of X-inactivation.
authors.affiliation: UFRGS, Porto Alegre, Brazil. loulapagesse@ibest.com.br
authors.forename: Louise Lapagesse
authors.initials: LL
authors.lastname: de Camargo Pinto
authors.forename: Sharbel Weidner
authors.initials: SW
authors.lastname: Maluf
authors.forename: Sandra
authors.initials: S
authors.lastname: Leistner-Segal
authors.forename: Camila
authors.initials: C
authors.lastname: Zimmer da Silva
authors.forename: Ana
authors.initials: A
authors.lastname: Brusius-Facchin
authors.forename: Maira Graef
authors.initials: MG
authors.lastname: Burin
authors.forename: Silvia
authors.initials: S
authors.lastname: Brustolin
authors.forename: Juan
authors.initials: J
authors.lastname: Llerena
authors.forename: Lucia
authors.initials: L
authors.lastname: Moraes
authors.forename: Leonardo
authors.initials: L
authors.lastname: Vedolin
authors.forename: Alice
authors.initials: A
authors.lastname: Schuch
authors.forename: Roberto
authors.initials: R
authors.lastname: Giugliani
authors.forename: Ida Vanessa Doederlein
authors.initials: IV
authors.lastname: Schwartz
mesh_terms: D001938:Brazil; D005260:Female; D006023:Glycoproteins / Q000097:blood; D006025:Glycosaminoglycans / Q000652:urine; D006579:Heterozygote; D006801:Humans; D007621:Karyotyping; D007668:Kidney / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D016532:Mucopolysaccharidosis II / Q000235:genetics* / Q000473:pathology*; D013154:Spleen / Q000473:pathology; D018709:Statistics, Nonparametric; D014057:Tomography, X-Ray Computed; D049951:X Chromosome Inactivation / Q000235:genetics*
chemical_list: D006023:Glycoproteins; D006025:Glycosaminoglycans; C018322:IDS protein, human