MYT1L-related developmental delay-intellectual disability-obesity syndrome

What it is

From: Orphanet

A rare neurodevelopmental syndrome characterized by global developmental delay, intellectual disability of varying severity or learning difficulties (e.g. dysphasia, dyspraxia, dyscalculia, dysgraphia) and behavioral disorders (stereotypies, autism spectrum disorder, impulsiveness or intolerance to frustration, self or hetero aggression). Additional clinical features include weight disorders (overweight/obesity) and eating behaviour disorders (including hyperphagia, tachyphagia, obsessive food compulsions), non-specific magnetic resonance imaging (brain MRI) abnormalities, ophthalmologic abnormalities, epilepsy, sleep disorders and non-specific dysmorphism. Endocrine abnormalities are rarely associated.

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.

Autistic behavior · Very frequent (99-80%)

Persistent deficits in social interaction and communication and interaction as well as a markedly restricted repertoire of activity and interest as well as repetitive patterns of behavior.

Delayed fine motor development · Very frequent (99-80%)

A type of motor delay characterized by a delay in acquiring the ability to control the fingers and hands.

Delayed speech and language development · Very frequent (99-80%)

A degree of language development that is significantly below the norm for a child of a specified age.

Global developmental delay · Very frequent (99-80%)

A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.

Intellectual disability · Very frequent (99-80%)

The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.

Abnormal eating behavior · Frequent (79-30%)

Abnormal eating habits involve excessive or insufficient consumption of food, or any other abnormal pattern of food consumption.

Abnormal repetitive mannerisms · Frequent (79-30%)

Use of the same abnormal action in response to certain triggers or at random. They may be used as a way to regulate one's internal state but must otherwise have no apparent functional purpose.

Aggressive behavior · Frequent (79-30%)

Behavior or an act aimed at harming a person, animal, or physical property (e.g., acts of physical violence; shouting, swearing, and using harsh language; slashing someone's tires).

Almond-shaped palpebral fissure · Frequent (79-30%)

A shape created by an acute downward arching of the upper eyelid and upward arching of the lower eyelid, toward the medial canthus, which gives the outline of the palpebral fissures the configuration of an almond. Thus, the maximum distance between the fissures is offset from, and medial to, the center point.

Attention deficit hyperactivity disorder · Frequent (79-30%)

Attention deficit hyperactivity disorder (ADHD) manifests at age 2-3 years or by first grade at the latest. The main symptoms are distractibility, impulsivity, hyperactivity, and often trouble organizing tasks and projects, difficulty going to sleep, and social problems from being aggressive, loud, or impatient.

Bulbous nose · Frequent (79-30%)

Increased volume and globular shape of the anteroinferior aspect of the nose.

Deeply set eye · Frequent (79-30%)

An eye that is more deeply recessed into the plane of the face than is typical.

Exaggerated cupid's bow · Frequent (79-30%)

More pronounced paramedian peaks and median notch of the Cupid's bow.

Fatigue · Frequent (79-30%)

A subjective feeling of tiredness characterized by a lack of energy and motivation.

Other findings in the same source

From: Orphanet

Additional reported features include Floppy infant (Frequent (79-30%)); Full cheeks (Frequent (79-30%)); Impulsivity (Frequent (79-30%)); Intellectual disability, moderate (Frequent (79-30%)); Motor delay (Frequent (79-30%)); Obesity (Frequent (79-30%)); Polyphagia (Frequent (79-30%)); Sleep abnormality (Frequent (79-30%)); Specific learning disability (Frequent (79-30%)); Abnormality of coordination (Frequent (79-30%)). This is a selected summary, not a complete description of the condition.

Inheritance in the source

From: Orphanet

Autosomal dominant

Understanding the inheritance label

From: MedlinePlus Genetics

An autosomal dominant pattern means that one altered copy of a relevant gene can be sufficient for the condition. Some affected people inherit the change; others have a new change without an affected parent. The precise finding, family history and condition determine what this means for relatives.

Which doctor should you see?

The suggested department for discussing MYT1L-related developmental delay-intellectual disability-obesity 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 MYT1L-related developmental delay-intellectual disability-obesity 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.