ESPE Abstracts

Introduction: Spondyloepimetaphyseal dysplasia (SEMD) (OMIM 603546) is a skeletal dysplasia that may present with a number of characteristics, including short stature, joint dislocations with laxity, limb malalignment and spinal deformity. It is believed that mutations in the KIF22 (kinesinfamilymember22) gene (16p11.2) may be the cause of this condition. In this case, we will present a case of leptodactylic type SEMD due to a KIF22 mutation.

Case: A 6-year-old girl presented with a history of short stature and curvature ofthe limbs since infancy. She was born at a weight of 2750 g with C/S at term. She underwent two surgical procedures due to congenital dislocation of the hip. At the age of five years, a right genuvalgum transiliac osteotomy wasperformed. It would appear that therewas a third-degree consanguinity between the parents. Upon examination, it was observed that the subject exhibited certain physical characteristics that could be considered dysmorphic, including midface hypoplasia, hip dislocation, diffuse joint laxity, and severe right genu valgum. Additionally, there were indications of diffuse bone deformities. The child's height was 95cm (-4.64SD), bodyweight was 14 kg (-2.98 SD), head circumference was 48cm (-2.19SD), the difference in height between the arm span was 8cm (+1/+2SD), the sitting height was 53.5cm (-2/-3SD), the ratio of the upper to the lower segment was1.28 (>+2SD). IGF-1:26.7ng/mL (< -2SD) IGF-BP3:780µg/mL (-1/meanSD). Thebone age assessment indicated that the patient was approximately two years of age. The bonesurvey indicated that the bones were somewhat porous and that there had been a slight reduction in height in themiddle and lower thoracic vertebra. It would appear that the fourth metacarpal bones mayhave been thinned inboth hands. The right femoral epiphysis appeared tobe somewhat sclerotic and smaller than it should be. It would be worth noting that there were vertical fine striations in the distal metaphysis of both femurs and the proximal-distal metaphysis of both tibia and fibula. It would appear that theremay havebeen some distal thinning in the 2nd, 3rd, and4th metatarsal bones of bothfeet.A genetic analysis revealed a heterozygousvariant inthe KIF22gene, specifically a c.443C>T (p.Pro148Leu) variant. It was evaluated according to ACGM criteria and classified as pathogenic.

Conclusion: In the context of severe short stature, it may be helpful to consider SEMD leptodactylic type in the presence of joint laxity and thinning ofthe fingers. SEMD leptodactylic type is a rare skeletaldysplasia, and we hope that by raising awareness, we can contribute to a better understanding of this condition.

Key Words: Short stature, Spondyloepimetaphyseal dysplasia type 2, KIF22