Kniest Dysplasia without Ocular and Auditory Abnormalities in a Boy of 12 Months.

Introduction: Kniest dysplasia is a rare skeletal disorder, characterized by mild dysmorphic features, cleft palate, short stature, short limbs, prominent joints, restricted joint mobility, hearing impairment, and ocular manifestations such as high-degree myopia, retinal detachment, and cataract. Typical radiological findings include platyspondyly, coronal clefts, and dumbbell-shaped long tubular bones.

Case presentation: Herein, we report on an 8-month-old boy who was referred to the pediatric genetic department due to narrow thorax and short extremities. He had mild dysmorphic features, cleft palate, narrow thorax, short extremities, and short stature. On radiographies, platyspondyly, hemivertebra, and dumbbell-shaped long tubular bones were detected. Clinical and radiological findings were consistent with Kniest dysplasia. Clinical exome sequencing was performed and revealed a heterozygous, pathogenic c.905C>T (p.Ala302Val) variant in the COL2A1 gene, confirming the initial clinical diagnosis.

Discussion: Kniest dysplasia is a very rare skeletal dysplasia, and an accurate clinical diagnosis is important to provide the best possible follow-up.