De Novo Mutation of Phex in a Type 1 Diabetes Patient

Program: Abstracts - Orals, Poster Previews, and Posters
Session: FRI 368-390-Metabolic Bone Disease Case Reports (posters)
Clinical
Friday, April 1, 2016: 1:15 PM-3:15 PM
Exhibit/Poster Hall (BCEC)

Poster Board FRI 383
Chen Fang*1, Zhimin Ma1, Yun Huang1, Heming Guo1 and Ji Hu2
1The second affiliated hospital of Soochow University, 2The second affiliated hospital of Soochow University, Suzhou, China
Background: X-linked hypophosphatemic rickets (XLH) is a dominant inherited disorder characterized by renal phosphate wasting, aberrant vitamin D metabolism, and abnormal bone mineralization. Inactivating mutations in the gene encoding phosphate-regulating gene with homologies to endopeptidases on the X chromosome (PHEX) have been found to be associated with XLH. The purpose of this study was to identify the genetic defect responsible for familial HR in a 4-generation Chinese Han pedigree.

Clinical case: We have sequenced all exons and intron–exon boundaries of the PHEX gene of all family members. Clinical features include, Short statue, bowing of leg,difficulty walking teeth abnormalities, and variable serum phosphate level in patients of this family. Herein ,we also identified a novel missense mutation at exon 4 (c.422 C > T) in proband and his family members, four family members had a heterozygous mutation, and the proband had a hemizygous mutation, The  mutation  c.422C>T  were predicted to be probably damaging when used PolyPhen-2 software. The residues Ser141 were shown to be perfectly conserved among humans, mice, rats, cow and chicken. Another striking clinical feature of this family, with a documented mutation of the PHEX gene, was the coexistence of type 1 diabetes in proband which is never reported before.

Conclusion: XLH in our patient is caused by a novel mutation within exon 4 of the PHEX gene. This is the first report of a de novo mutation of PHEX in a type 1 diabetes patient, and heterozygous mutation in the other family member did not appear to influence blood glucose homeostasis.

Nothing to Disclose: CF, ZM, YH, HG, JH

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