Intellectual disability-seizures-hypophosphatasia-ophthalmic-skeletal anomalies syndrome

What it is

From: Orphanet

A rare congenital disorder of glycosylation characterized by neonatal hypotonia, global development delay, developmental regress and severe to profound intellectual disability, infantile onset seizures that are initially associated with febrile episodes with subsequent transition to unprovoked seizures, impaired vision with esotropia and nystagmus, progressive cerebral and cerebellar atrophy, skeletal abnormalities (including brachycephaly, scoliosis, slender long bones, delayed bone age, pectus excavatum and osteopenia), inverted nipples and dysmorphic features including high and narrow forehead, frontal bossing, short nose, depressed nasal bridge, anteverted nares, high palate and wide open mouth consistent with facial hypotonia. Other features may include cardiac abnormalities (such as patent ductus arteriosus, atrial septal defects), urogenital abnormalities (such as nephrocalcinosis, urolithiasis), and low plasma concentration of alkaline phosphatase.

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.

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

An abnormality of the form, structure, or size of the skeletal system.

Brachycephaly · Very frequent (99-80%)

An abnormality of skull shape characterized by a decreased anterior-posterior diameter. That is, a cephalic index greater than 81%. Alternatively, an apparently shortened anteroposterior dimension (length) of the head compared to width.

Cerebral visual impairment · Very frequent (99-80%)

A form of loss of vision caused by damage to the visual cortex rather than a defect in the eye.

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

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

High forehead · Very frequent (99-80%)

An abnormally increased height of the forehead.

Hypotonia · Very frequent (99-80%)

Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.

Intellectual disability, severe · Very frequent (99-80%)

Severe intellectual disability (ID) is defined as a type of ID characterized by severely sub-average adaptive functioning and intellectual functioning, with an intelligence quotient (IQ) the range of 20-34.

Long philtrum · Very frequent (99-80%)

Distance between nasal base and midline upper lip vermilion border more than 2 SD above the mean. Alternatively, an apparently increased distance between nasal base and midline upper lip vermilion border.

Narrow forehead · Very frequent (99-80%)

Width of the forehead or distance between the frontotemporales is more than two standard deviations below the mean (objective); or apparently narrow intertemporal region (subjective).

Nystagmus · Very frequent (99-80%)

Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.

Osteopenia · Very frequent (99-80%)

Osteopenia is a term to define bone density that is not normal but also not as low as osteoporosis. By definition from the World Health Organization osteopenia is defined by bone densitometry as a T score -1 to -2.5.

Slender long bone · Very frequent (99-80%)

Reduced diameter of a long bone.

Strabismus · Very frequent (99-80%)

A misalignment of the eyes so that the visual axes deviate from bifoveal fixation. The classification of strabismus may be based on a number of features including the relative position of the eyes, whether the deviation is latent or manifest, intermittent or constant, concomitant or otherwise and according to the age of onset and the relevance of any associated refractive error.

Abnormal eye physiology · Frequent (79-30%)

A functional anomaly of the eye.

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal heart morphology (Frequent (79-30%)); Abnormality of the urinary system (Frequent (79-30%)); Bilateral tonic-clonic seizure (Frequent (79-30%)); Congenital megaureter (Frequent (79-30%)); Decreased circulating alkaline phosphatase activity (Frequent (79-30%)); Delayed skeletal maturation (Frequent (79-30%)); Downturned corners of mouth (Frequent (79-30%)); Generalized myoclonic seizure (Frequent (79-30%)); Generalized tonic seizure (Frequent (79-30%)); Hearing impairment (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

When it may begin

From: Orphanet

Infancy; Neonatal

Inheritance in the source

From: Orphanet

Autosomal recessive

Frequency and the population described

From: Orphanet

Reported case(s): 4.0; 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 Intellectual disability-seizures-hypophosphatasia-ophthalmic-skeletal anomalies syndrome is Neurology, with a neurologist 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.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Intellectual disability-seizures-hypophosphatasia-ophthalmic-skeletal anomalies syndrome. 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.