PYKNODYSOSTOSIS (OSTEOPETROSIS ACRO-OSTEOLYTICA)

Area of Science:

• Genetics
• Orthopedics
• Endocrinology

Background:

• Pyknodysostosis (PKND) is a rare autosomal recessive skeletal dysplasia characterized by osteosclerosis and bone fragility.
• It results from mutations in the cathepsin K (CTSK) gene, crucial for osteoclast function.
• PKND often presents with a constellation of distinctive features but can be misdiagnosed or overlooked.

Observation:

• A 21-year-old female with disproportionate short stature, bilateral blindness from optic nerve canal thickening, and recurrent foot fractures was evaluated.
• Physical examination revealed characteristic features including open fontanels, frontal bossing, micrognathia, and digital abnormalities.
• Radiographic findings showed diffuse bone sclerosis, cortical thickening, and acro-osteolysis, with markedly increased bone mineral density.

Findings:

• Genetic testing confirmed a homozygous mutation in the CTSK gene, establishing the diagnosis of pyknodysostosis.
• The patient presented with classic clinical and radiographic manifestations of PKND, despite a long history of being undiagnosed.
• Consanguinity in the family suggested a potential genetic inheritance pattern.

Implications:

• This case underscores the importance of recognizing classic features of pyknodysostosis to avoid diagnostic delays.
• Increased clinical awareness and genetic testing are crucial for timely diagnosis and management of PKND.
• Early diagnosis can potentially guide management strategies and genetic counseling for affected families.