Langer mesomelic dysplasia

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Langer mesomelic dysplasia is a disorder of bone growth. Affected individuals typically have extreme shortening of the long bones in the arms and legs (mesomelia). As a result of the shortened leg bones, people with Langer mesomelic dysplasia have very short stature. A bone in the forearm called the ulna and a bone in the lower leg called the fibula are often underdeveloped or absent, while other bones in the forearm (the radius) and lower leg (the tibia) are unusually short, thick, and curved. Some people with Langer mesomelic dysplasia also have an abnormality of the wrist and forearm bones called Madelung deformity, which may cause pain and limit wrist movement. Additionally, some affected individuals have mild underdevelopment of the lower jaw bone (mandible).

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Langer mesomelic dysplasia results from changes involving the SHOX gene. The protein produced from this gene plays a role in bone development and is particularly important for the growth and maturation of bones in the arms and legs. The most common cause of Langer mesomelic dysplasia is a deletion of the entire SHOX gene. Other genetic changes that can cause the disorder include mutations in the SHOX gene or deletions of nearby genetic material that normally helps regulate the gene's activity. These changes greatly reduce or eliminate the amount of SHOX protein that is produced. A lack of this protein disrupts normal bone development and growth, which underlies the severe skeletal abnormalities associated with Langer mesomelic dysplasia.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Langer mesomelic dysplasia has a pseudoautosomal recessive pattern of inheritance. The SHOX gene is located on both the X and Y chromosomes (sex chromosomes) in an area known as the pseudoautosomal region. Although many genes are unique to either the X or Y chromosome, genes in the pseudoautosomal region are present on both sex chromosomes. As a result, both females (who have two X chromosomes) and males (who have one X and one Y chromosome) normally have two functional copies of the SHOX gene in each cell. The inheritance pattern of Langer mesomelic dysplasia is described as recessive because both copies of the SHOX gene in each cell must be missing or altered to cause the disorder. In females, the condition results when the gene is missing or altered on both copies of the X chromosome; in males, it results when the gene is missing or altered on the X chromosome and the Y chromosome.

A related skeletal disorder called Léri-Weill dyschondrosteosis occurs when one copy of the SHOX gene is mutated in each cell. This disorder has signs and symptoms that are similar to, but typically less severe than, those of Langer mesomelic dysplasia.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

The prevalence of Langer mesomelic dysplasia is unknown, although the condition appears to be rare. Several dozen affected individuals have been reported in the scientific literature.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Abnormal carpal morphology · Very frequent (99-80%)

An abnormality affecting the carpal bones of the wrist (scaphoid, lunate, triquetral, pisiform, trapezium, trapezoid, capitate, hamate).

Abnormal morphology of ulna · Very frequent (99-80%)

Any structural anomaly of the ulna, a bone of the forearm the extends from the elbow to the little finger.

Abnormality of epiphysis morphology · Very frequent (99-80%)

An anomaly of epiphysis, which is the expanded articular end of a long bone that developes from a secondary ossification center, and which during the period of growth is either entirely cartilaginous or is separated from the shaft by a cartilaginous disk.

Aplasia/Hypoplasia of the fibula · Very frequent (99-80%)

Absence or underdevelopment of the fibula.

Bowing of the long bones · Very frequent (99-80%)

A bending or abnormal curvature of a long bone.

Disproportionate short-limb short stature · Very frequent (99-80%)

A type of disproportionate short stature characterized by a short limbs but an average-sized trunk.

High palate · Very frequent (99-80%)

Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).

Madelung deformity · Very frequent (99-80%)

An anomaly related to partial closure, or failure of development of the ulnar side of the distal radial growth plate, which results in an arrest of epiphyseal growth of the medial and volar portions of the distal radius. This leads to shortening of the radius and relative overgrowth of the ulna.

Other findings in the same source

From: Orphanet

Additional reported features include Micromelia (Very frequent (99-80%)); Severe short stature (Very frequent (99-80%)); Short femoral neck (Very frequent (99-80%)); Ulnar deviation of finger (Very frequent (99-80%)); Mesomelic/rhizomelic limb shortening (Very frequent (99-80%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Langer mesomelic dysplasia is Orthopaedics, with a orthopaedic specialist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• What explains the change in pain, movement or function?
• Which activities need adjustment while the diagnosis is being clarified?
• What are the roles of rehabilitation, observation and surgery in this situation?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Langer mesomelic dysplasia. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.