Meyahealth
HomeGeneticsConditionPyle disease
Back to Condition
Pyle disease
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Pyle disease

Pyle disease is a rare bone disorder characterized by abnormally broad ends of the long bones, which leads to bone fragility and increased risk of fractures.

Overview

Pyle disease is a disorder of the bones. Its hallmark feature is an abnormality of the long bones in the arms and legs in which the ends (metaphyses) of the bones are abnormally broad; the shape of the bones resembles a boat oar or paddle. The broad metaphyses are due to enlargement of the spongy inner layer of bone (trabecular bone). Although trabecular bone is expanded, the dense outermost layer of bone (cortical bone) is thinner than normal. As a result, the bones are fragile and fracture easily. The bone abnormalities in the legs commonly cause knock knees in affected individuals.

Other bone abnormalities can also occur in Pyle disease. Affected individuals may have widened collar bones (clavicles), ribs, or bones in the fingers and hands. Dental problems are common in Pyle disease, including delayed appearance (eruption) of permanent teeth and misalignment of the top and bottom teeth (malocclusion).

Frequency

Pyle disease is thought to be a rare disorder, although its prevalence is unknown. More than 25 cases have been described in the medical literature.

Causes

Pyle disease is caused by mutations in the SFRP4 gene. This gene provides instructions for making a protein that blocks (inhibits) a process called Wnt signaling, which is involved in the development of several tissues and organs throughout the body. In particular, regulation of Wnt signaling by the SFRP4 protein is critical for normal bone development and remodeling. Bone remodeling is a normal process in which old bone is broken down and new bone is created to replace it. Mutations in the SFRP4 gene are thought to prevent the production of functional SFRP4 protein. The resulting dysregulation of Wnt signaling leads to the bone abnormalities characteristic of Pyle disease.

Gene Associated with Pyle Disease

  • SFRP4

Inheritance

Pyle disease is inherited in an autosomal recessive pattern, which means both copies of the SFRP4 gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene. While they do not develop the condition, they may have mild abnormalities of the long bones.

Frequently Asked Questions

High‑impact and contact activities such as basketball, soccer, gymnastics, and skateboarding place the most stress on the already thin cortical bone and should be avoided or modified. Low‑impact exercises like swimming, stationary cycling, and gentle stretching help maintain muscle strength without excessive force on the skeleton.
Bisphosphonate therapy has been used off‑label to increase bone mineral density in some patients, but evidence is limited. A multidisciplinary plan that includes weight‑bearing physiotherapy, calcium (1,000–1,200 mg/day) and vitamin D supplementation (800–1,000 IU/day), and regular bone density monitoring is the current standard of care.
Schedule dental examinations every six months to monitor eruption timing and alignment. Early referral to a pediatric orthodontist is advised if delayed eruption or malocclusion is noted, as orthodontic appliances may be needed to guide proper bite development. Good oral hygiene and fluoride treatments can also reduce the risk of caries in teeth that erupt later.
Fractures in Pyle disease often occur after low‑impact events (e.g., a stumble from standing) and may be accompanied by pain at the widened metaphysis of the long bone. X‑rays typically show markedly broadened, “boat‑shaped” ends of the bone with thin cortical margins, which distinguishes them from ordinary fractures.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ