The Role of Genetic Mutations in the HPGD & SLCO2A1 Genes in Pachydermoperiostosis Syndrome

Pachydermoperiostosis, also known as Primary Hypertrophic Osteoarthropathy (PHO), is a rare genetic disorder. The three main features are: enlarged fingertips (clubbing), thickened facial skin (pachydermia), and excessive sweating (hyperhidrosis). PHO is characterized by problems with skin and bone growth. Patients with PHO usually have coarse facial features with oily, thick, grooved skin on the face, joint pain, enlarged fingertips and toes, and hyperhidrosis of the hands and feet. Symptoms vary individually; however, men generally present with more severe manifestations. X-rays can help check for features that are not noticeable to the naked eye. There are two genes that are associated with PHO: the HPGD gene, located on the long arm of chromosome 4 at 4q34.1, and the SLCO2A1 gene, located on the long arm of chromosome 3 at 3q22.1 - q22.2. Mutations in the HPGD gene are inherited in an autosomal recessive manner, and the condition is sometimes abbreviated as PHOAR1 or Touraine-Solente-Gole syndrome.