Phenotypic variability in children with Bruck syndrome type 2: Clinical cases

BACKGROUND: Bruck syndrome is a rare disorder that features osteogenesis imperfecta, combined with severe congenital joint contractures often with pterygia, short stature, severe limb deformities, and progressive scoliosis. Its two forms, Bruck syndrome types 1 and 2, have similar clinical manifestations without osomal recessive inheritance and are caused by pathogenic variants of the nucleotide sequences in the FKBP10 and PLOD2 genes, respectively. CLINICAL CASES: The article demonstrates phenotypic and radiographic features as well as laboratory values of siblings with Bruck syndrome type 2 (a 10-year-old boy and a 13-year-old girl) born to healthy parents in a consanguineous marriage. The boy had congenital flexion contractures of the knee and elbow joints, few fractures, and severe kyphoscoliosis. The girl had no congenital joint contractures but had kyphoscoliosis, more severe osteoporosis, and a history of having more fractures than her younger brother. DISCUSSION: The cases demonstrated the significant phenotypic intrafamilial variability of Bruck syndrome type 2, caused by a newly identified homozygous variant c.1885AG (p.Thr629Ala) in PLOD2, which consists of varying degrees of osteoporosis, and the presence and severity of contractures. CONCLUSIONS: The description of the given clinical observation was made to draw attention to a rare pathology and expand doctors’ knowledge about the variability of clinical manifestations of Bruck syndrome. Genetic diagnostics is necessary for the timely diagnosis of Bruck syndrome, determining the prognosis and developing patient management techniques.