A Novel Premature Termination Codon Mutation in TRAPPC2 Is Associated with X-Linked Spondyloepiphyseal Dysplasia Tarda.

Introduction: Spondyloepiphyseal dysplasia tarda (SEDT) is an inherited disorder that is typically diagnosed in childhood or adolescence. It is characterized by disproportionate short stature and premature osteoarthritis, and it frequently affects males. Here, we described a novel nonsense mutation, c.406A>T; p(Lys136Ter), in TRAPPC2 (NM_001011658.4) in a Turkish patient with X-linked SEDT.

Case presentation: A 15-year-old boy, born to non-consanguineous Turkish parents, exhibited a decline in height velocity over 3 years and complained of back pain despite minimal physical activity. Growth and development were normal until adolescence, with the patient's weight at 35 kg (SDS -3.85), height at 134 cm (SDS -5.44), and a predicted adult height of 137.6 cm. Dysmorphic facial features, microtia, synophrys, hypotelorism, and barrel chest were noted. Radiological examination revealed osteopenic bone structure, hypoplastic odontoid process, platyspondyly, scoliosis, short femoral necks, and coxa vara. Genetic analysis identified a hemizygous novel stop codon mutation (c.406A>T; pLys136Ter) in TRAPPC2, also detected as heterozygous in the patient's mother.

Conclusion: In adolescence or childhood, X-linked SEDT should be considered in cases of disproportionate short stature, short trunk, osteoarthritis, and a family history that is appropriate for X-linked inheritance. Skeletal survey should be performed to suspect SEDT, and radiological findings may support diagnosis.