Exome sequencing and functional follow-up identifies KIF26B as a novel genetic determinant of familial osteoporosis

Abstract

OBJECTIVE: Osteoporosis is a skeletal disease under strong genetic control. The aim of the study was to identify the genetic determinants of primary osteoporosis in a Maltese family and investigate the function of identified novel genes and variants.

METHODS: A 2-generation family of 12 recruited relatives (including 7 siblings) with ages ranging from 34-77 years was tested. Osteoporosis was defined using DXA scans of the lumbar spine (LS) and hip. The proband had a LS T-score of -4.0. Exome sequencing was performed on 6 well-phenotyped relatives and replication of shortlisted variants was sought in a case-control collection of Maltese postmenopausal women (n=1012). In vitro protein expression was analyzed by transfecting in COS-7 cells and western blotting, whereas consequences of gene knockdown was studied in a zebrafish model. BMD was assessed with micro-computed tomography; mineralization rate with Alizarin red staining of the whole fish skeleton; and resorption activity with TRAcP staining of regenerating scales.

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