Opsismodysplasia

What it is

From: Orphanet

A rare skeletal dysplasia characterized by pre-or postnatal severe rhizomelic micromelia with short long bones (congenital dwarfism), extremely short feet and hands, major delay in skeletal ossification, metaphyseal cupping, severe platyspondyly, muscular hypotonia and facial dysmorphism (including macrocephaly, large anterior fontanelle, arched and prominent eyebrows, hypertelorism, exophthalmos, depressed nasal bridge, small anteverted nose with relatively broad nares, long philtrum and thin upper lip). Patients also present with short neck, narrow, bell-shaped thorax. Circumferential skin creases (especially in the upper arms, hands, and feet) and recurrent respiratory tract infections (that followed a fatal course in some cases) have also been reported.

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 metaphysis morphology · Very frequent (99-80%)

An abnormality of one or more metaphysis, i.e., of the somewhat wider portion of a long bone that is adjacent to the epiphyseal growth plate and grows during childhood.

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.

Abnormally ossified vertebrae · Very frequent (99-80%)

An abnormality of the formation and mineralization of one or more vertebrae.

Brachydactyly · Very frequent (99-80%)

Digits that appear disproportionately short compared to the hand/foot. The word brachydactyly is used here to describe a series distinct patterns of shortened digits (brachydactyly types A-E). This is the sense used here.

Delayed skeletal maturation · Very frequent (99-80%)

A decreased rate of skeletal maturation. Delayed skeletal maturation can be diagnosed on the basis of an estimation of the bone age from radiographs of specific bones in the human body.

Depressed nasal bridge · Very frequent (99-80%)

Posterior positioning of the nasal root in relation to the overall facial profile for age.

Frontal bossing · Very frequent (99-80%)

Bilateral bulging of the lateral frontal bone prominences with relative sparing of the midline.

Hypoplastic ischia · Very frequent (99-80%)

Underdevelopment of the ischium, which forms the lower and back part of the hip bone.

Hypoplastic pubic bone · Very frequent (99-80%)

Underdevelopment of the pubis, which together with the ilium and the ischium, is one of the three bones that make up the hip bone.

Large fontanelles · Very frequent (99-80%)

In newborns, the two frontal bones, two parietal bones, and one occipital bone are joined by fibrous sutures, which form a small posterior fontanelle, and a larger, diamond-shaped anterior fontanelle. These regions allow for the skull to pass the birth canal and for later growth. The fontanelles gradually ossify, whereby the posterior fontanelle usually closes by eight weeks and the anterior fontanelle by the 9th to 16th month of age. Large fontanelles are diagnosed if the fontanelles are larger than age-dependent norms.

Macrocephaly · Very frequent (99-80%)

Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.

Severe short stature · Very frequent (99-80%)

A severe degree of short stature, more than -4 SD from the mean corrected for age and sex.

Short nose · Very frequent (99-80%)

Distance from nasion to subnasale more than two standard deviations below the mean, or alternatively, an apparently decreased length from the nasal root to the nasal tip.

Squared iliac bones · Very frequent (99-80%)

A shift from the normally round (convex) appearance of the iliac wing towards a square-like appearance.

Other findings in the same source

From: Orphanet

Additional reported features include Tapered finger (Very frequent (99-80%)); Hypoplastic vertebral bodies (Very frequent (99-80%)); Respiratory insufficiency (Very frequent (99-80%)); Flat occiput (Frequent (79-30%)); Hypotonia (Frequent (79-30%)); Recurrent respiratory infections (Frequent (79-30%)); Blue sclerae (Occasional (29-5%)); Broad thumb (Occasional (29-5%)); Hepatomegaly (Occasional (29-5%)); Joint stiffness (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Reported case(s): 30.0; Worldwide. This is a published case count, not prevalence. Point prevalence: <1 / 1 000 000; Worldwide; Class only.

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal recessive pattern usually involves disease-causing changes in both copies of a gene. Parents may each carry one altered copy without having the condition themselves. A genetic counsellor can explain carrier testing and reproductive implications using the actual laboratory findings, rather than the condition name alone.

Which doctor should you see?

The suggested department for discussing Opsismodysplasia 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 Opsismodysplasia. 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.