Leri Pleonosteosis is an extremely rare inherited disorder characterized by unusual, flattened facial features, abnormalities of the hands and feet, skeletal malformations, short stature, and/or limitation of joint movements. Characteristic abnormalities of the hands and feet may include unusually broad and/or short thumbs and great toes (brachydactyly) that may be bent outward from the body (valgus position); as a result, the hands may have a "spade-shaped" appearance. Skeletal malformations may include knees that are bent backward (genu recurvitum) and abnormal enlargement of the cartilaginous structures that surround the upper portion of the spinal cord (posterior neural arches of the cervical vertebrae). In addition, affected individuals may develop thickened tissue on the palms (palmar) and forearms. Symptoms may vary from case to case. Leri pleonosteosis is inherited as an autosomal dominant genetic trait.
Infants with this disorder typically have a flattened facial appearance that may be similar to that of infants with Down syndrome. In rare cases, affected infants may also have an abnormally narrow distance between the upper and lower eyelids (blepharophimosis) and/or an unusually small part of the eye through which light passes (microcornea).
Children with Leri pleonosteosis may not grow at the expected rate and eventually exhibit short stature. They may also exhibit various skeletal abnormalities including stiff joints and, in severe cases, joints that are fixed in a permanently flexed position (contractures). In some cases, the cartilage that surrounds the upper portion of the spinal cord (posterior neural arches of the cervical vertebrae) may be unusually thick and overgrown. In addition, affected individuals may have knees that are bent backward (genu recurvatum). Such skeletal abnormalities may result in limitation of movement, and affected individuals may have an unusual shuffling, short-stepped manner of walking (gait).
Other skeletal malformations associated with Leri pleonosteosis typically affect the hands and feet. Many infants with this disorder have abnormally short and/or broad fingers (brachydactyly), giving the hands a “spade-shaped” appearance; the toes may also be affected. In addition, the thumbs and great toes may be bent outward from the body (valgus position). In some cases, affected children may develop abnormally dense fibrous tissue (fasciae) on the palms, forearms, and/or feet. Overgrowth (hyperplasia) of fibrous tissue may, in some cases, cause compression of nerves of the feet and/or wrists, resulting in pain, tenderness, and/or other symptoms (e.g., Morton metatarsalgia and/or carpal tunnel syndrome). (For more information on these conditions, see the Related Disorders section of this report.) In some rare cases, affected individuals also develop compression of certain nerves of the upper part of the spinal cord.
When it was first identified, researchers believed that the signs of the disorder were due to the premature hardening (pleonosteosis) of the end portions of the long bones (epiphyses). However, since that time, some researchers have speculated that the basic abnormality may be the pulling away of specialized connective tissue (periosteal traction) from the shafts of the long bones (metaphyses).
Leri pleonosteosis is inherited as an autosomal dominant genetic trait. Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Human body cells normally have 46 chromosomes. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y. Males have one X and one Y chromosome and females have two X chromosomes. Each chromosome has a short arm designated “p” and a long arm designated “q”. Chromosomes are further sub-divided into many bands that are numbered. For example, “chromosome 11p13″ refers to band 13 on the short arm of chromosome 11. The numbered bands specify the location of the thousands of genes that are present on each chromosome.
Genetic diseases are determined by the combination of genes for a particular trait that are on the chromosomes received from the father and the mother.
All individuals carry a few abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.
Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.
Leri pleonosteosis is an extremely rare inherited disorder that affects males and females in equal numbers. Approximately 20 cases have been reported worldwide, with most of these outside of North America. The symptoms and physical characteristics associated with Leri pleonosteosis usually become apparent during infancy or early childhood.
The diagnosis of Leri pleonosteosis may be established by a thorough clinical evaluation, characteristic physical findings, detailed patient history, and/or specialized tests including advanced imaging techniques (e.g., various x-ray methods). For example, enlargement of the cartilage that surrounds the upper spinal cord (posterior neural arches of the cervical vertebrae), is an important characteristic of this disorder and is potentially detectable by x-ray studies.
The treatment of Leri pleonosteosis is directed toward the specific symptoms that are apparent in each individual. Treatment may require the coordinated efforts of a team of specialists. Pediatricians, specialists who diagnose and treat skeletal abnormalities (orthopedic specialists), and other healthcare professionals may need to systematically and comprehensively plan an affected child's treatment.
Children with Leri pleonosteosis should be observed for possible spinal cord compression that is sometimes associated with this disorder. Physical therapy may be recommended to help improve an affected individual's ability to walk and perform other movements independently (mobility). Other treatment is symptomatic and supportive.
Genetic counseling will be of benefit for affected individuals and their families. A team approach for infants and children with this disorder may be of benefit and may include special social, educational, and medical services.
Research on genetic disorders and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic and familial disorders in the future.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
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McKusick VA, ed. Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Entry Number;151200 : Last Edit Date;3/18/2004.
Leri pleonosteosis. Orphanet. nd. 1p.