title: Various types of LRP5 mutations in four patients with osteoporosis-pseudoglioma syndrome: identification of a 7.2-kb microdeletion using oligonucleotide tiling microarray.
abstract: Osteoporosis-pseudoglioma syndrome (OPS; OMIM 259770) is an autosomal-recessive genetic disorder characterized by severe osteoporosis and visual disturbance from childhood. Biallelic mutations in the low-density lipoprotein receptor-related protein 5 gene (LRP5) have been frequently detected, while a subset of patients had only one or no detectable mutation. We report on the clinical and molecular findings of four unrelated Japanese patients with the syndrome. The four patients had typical skeletal and ocular phenotypes of OPS, namely severe juvenile osteoporosis and early-onset visual disturbance, with or without mental retardation. We undertook standard PCR-based sequencing for LRP5 and found four missense mutations (p.L145F, p.T244M, p.P382L, and p.T552M), one nonsense mutation (p.R1534X), and one splice site mutation (c.1584+1G>A) among four OPS patients. Although three patients had two heterozygous mutations, one had only one heterozygous splice site mutation. In this patient, RT-PCR from lymphocytic RNA demonstrated splice error resulting in 63-bp insertion between exons 7 and 8. Furthermore, the patient was found to have only mutated RT-PCR fragment, implying that a seemingly normal allele did not express LRP5 mRNA. We then conducted custom- designed oligonucleotide tiling microarray analyses targeted to a 600-kb genome region harboring LRP5 and discovered a 7.2-kb microdeletion encompassing exons 22 and 23 of LRP5. We found various types of LRP5 mutations, including an exon-level deletion that is undetectable by standard PCR-based mutation screening. Oligonucleotide tiling microarray seems to be a powerful tool in identifying cryptic structural mutations.
authors.affiliation: Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Narumi
authors.forename: Chikahiko
authors.initials: C
authors.lastname: Numakura
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiihara
authors.forename: Chizuru
authors.initials: C
authors.lastname: Seiwa
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Nozaki
authors.forename: Takanori
authors.initials: T
authors.lastname: Yamagata
authors.forename: Mariko Y
authors.initials: MY
authors.lastname: Momoi
authors.forename: Yoriko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshino
authors.forename: Toyojiro
authors.initials: T
authors.lastname: Matsuishi
authors.forename: Eriko
authors.initials: E
authors.lastname: Nishi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawame
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Akahane
authors.forename: Gen
authors.initials: G
authors.lastname: Nishimura
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Emi
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Hasegawa
mesh_terms: D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D002648:Child; D017931:DNA Primers; D005260:Female; D005910:Glioma / Q000235:genetics*; D006801:Humans; D026502:LDL-Receptor Related Proteins / Q000235:genetics*; D060492:Low Density Lipoprotein Receptor-Related Protein-5; D008297:Male; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D010024:Osteoporosis / Q000235:genetics*; D010375:Pedigree; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017384:Sequence Deletion; D013577:Syndrome
chemical_list: D017931:DNA Primers; D026502:LDL-Receptor Related Proteins; C555482:LRP5 protein, human; D060492:Low Density Lipoprotein Receptor-Related Protein-5