Autosomal recessive primary hypertrophic osteoarthropathy1 (PHOAR1) is characterized by delayed closure of the fontanels, digital clubbing, arthropathy and periostosis. Homozygous mutations in hydroxyprostaglandin dehydrogenase (HPGD) gene are the underlying pathology of PHOAR1. The aim of this study was to analyze the HPGD gene and the changing clinical and radiological findings with advancing age of two siblings with the diagnosis of PHOAR1. A novel 2-bp homozygous deletion was found in exon 3 (c.310-311delCT) of HPGD gene in the patients. Clinical and radiological findings of the siblings were evaluated between 4 months and 8 years and 6 months of age. The painful swelling and sweating of the hands and feet, cranial ossification defect and expanded diaphyses were evident at infantile period and gradually showed improvement until 4 years of age. After the age of 4 years, digital clubbing and swelling of knees persisted, palmoplantar hyperkeratosis developed and acro-osteolysis became evident on hand radiographs. In conclusion, we suggest that the clinical findings of the patients with PHOAR1 should be classified in two periods as early and late childhood. We also observed that there was intrafamilial variability of clinical findings.