Traits

Traits linked to MECP2

methyl-CpG binding protein 2

The Human Phenotype Ontology links 250 traits to MECP2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
Absent speech development	Always
Apraxia	Always
Brief seizures with staring spells	Always
Delayed ability to roll over	Always
Delayed ability to sit	Always
Delayed ability to walk	Always
Delayed speech and language development	Always
Dystonia	Always
Encephalopathy	Always
Epilepsy	Always
Global developmental delay	Always
Intellectual disability	Always
Intellectual disability, mild	Always
Intellectual disability, severe	Always
IQ less than 20	Always
Loss of developmental milestones	Always
Persistent head lag	Always
Poor eye contact	Always
Progressive degeneration of movement	Always
Repeated seizures without recovery between them	Always
Repetitive compulsive behavior	Always
Resting tremor	Always
Restlessness	Always
Severe global developmental delay	Always
Slow movements	Always
Stereotypical hand wringing	Always
Tonic seizure	Always
Abnormal gait	Very often (80–99%)
Abnormal speech pattern	Very often (80–99%)
Abnormality of movement	Very often (80–99%)
Agitation	Very often (80–99%)
Autism spectrum disorder	Very often (80–99%)
Chorea	Very often (80–99%)
Difficulty sleeping	Very often (80–99%)
EEG abnormality	Very often (80–99%)
Hyperactive deep tendon reflexes	Very often (80–99%)
Involuntary movements	Very often (80–99%)
Irritability	Very often (80–99%)
Loss of acquired spoken language	Very often (80–99%)
Loss of speech	Very often (80–99%)
More active than typical	Very often (80–99%)
Progressive language deterioration	Very often (80–99%)
Recurrent hand flapping	Very often (80–99%)
Repetitive movements	Very often (80–99%)
Aggressive behavior	Often (30–79%)
Anxiety	Often (30–79%)
Bipolar disorder	Often (30–79%)
Choreoathetosis	Often (30–79%)
EEG with focal slow activity	Often (30–79%)
EEG with generalized slow activity	Often (30–79%)
Focal EEG discharges with secondary generalization	Often (30–79%)
Grand mal seizures	Often (30–79%)
Hand apraxia	Often (30–79%)
Inability to coordinate movements when walking	Often (30–79%)
Inability to speak	Often (30–79%)
Inability to walk	Often (30–79%)
IQ between 34 and 49	Often (30–79%)
Limb apraxia	Often (30–79%)
Limb myoclonus	Often (30–79%)
Loss of ability to walk	Often (30–79%)
Loss of acquired purposeful hand skills	Often (30–79%)
Neonatal seizure	Often (30–79%)
Overactive lower leg reflex	Often (30–79%)
Pain insensitivity	Often (30–79%)
Poor social interactions	Often (30–79%)
Restrictive behavior	Often (30–79%)
Teeth grinding	Often (30–79%)
Tongue thrusting	Often (30–79%)
Tremor	Often (30–79%)
Abnormal autonomic nervous system physiology	Sometimes (5–29%)
Abnormal fear-induced behavior	Sometimes (5–29%)
Can't control feelings	Sometimes (5–29%)
Degeneration of cerebrum	Sometimes (5–29%)
Delayed motor skills	Sometimes (5–29%)
Depression	Sometimes (5–29%)
Developmental stagnation	Sometimes (5–29%)
Generalized myoclonic seizure	Sometimes (5–29%)
Impaired pain sensation	Sometimes (5–29%)
Inappropriate crying	Sometimes (5–29%)
Inappropriate laughter	Sometimes (5–29%)
Infantile spasms	Sometimes (5–29%)
More grooves in brain	Sometimes (5–29%)
Multifocal epileptiform discharges	Sometimes (5–29%)
Panic attack	Sometimes (5–29%)
Parkinsonism	Sometimes (5–29%)
Pill-rolling tremor	Sometimes (5–29%)
Psychosis	Sometimes (5–29%)
Shuffled walk	Sometimes (5–29%)
Stooped posture	Sometimes (5–29%)
Wide based walk	Sometimes (5–29%)
Ataxia	Not recorded
Autism	Not recorded
Babinski sign	Not recorded
Boiling mad	Not recorded
Decrease in size of the outer layer of the brain due to loss of brain cells	Not recorded
Gait apraxia	Not recorded
Impaired use of nonverbal behaviors	Not recorded
Increased reflexes	Not recorded
Inflexible adherence to routines	Not recorded
Instability or lack of coordination of central trunk muscles	Not recorded
Jerking	Not recorded
Lack of peer relationships	Not recorded
Lack of spontaneous play	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Always
Decreased facial muscle tone	Always
Drooling	Always
Zygomatic flattening	Always
Drooping lower lip	Very often (80–99%)
Eye folds	Very often (80–99%)
Narrow opening between the eyelids	Very often (80–99%)
Progressively abnormally small cranium	Very often (80–99%)
Tented mouth	Very often (80–99%)
Development of small head that was not present at birth	Often (30–79%)
Midface retrusion	Often (30–79%)
Abnormal color of the oral mucosa	Sometimes (5–29%)
Abnormality of salivation	Sometimes (5–29%)
Big calvaria	Sometimes (5–29%)
Broad head shape	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Inflammation of the lips	Sometimes (5–29%)
Mouth sore	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Prominent nasal bridge	Sometimes (5–29%)
Upward slanting of the opening between the eyelids	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)
Widely spaced teeth	Sometimes (5–29%)
Small head present at birth	Rarely (1–4%)
Abnormal dentition	Not recorded
Depressed nasal bridge	Not recorded
Disturbance of facial expression	Not recorded
Excessive salivation	Not recorded
Little lower jaw	Not recorded
Narrow mouth	Not recorded
Short neck	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Decreased muscle tone in infant	Always
Flexed joint that cannot be straightened	Always
Low muscle tone	Always
Low muscle tone in trunk	Always
Scoliosis	Always
Spastic paraplegia	Always
Spastic tetraplegia	Always
Delayed bone maturation	Very often (80–99%)
Functional motor deficit	Very often (80–99%)
Lower limb spasticity	Very often (80–99%)
Abnormal muscle tone	Often (30–79%)
Arthritis	Often (30–79%)
Funnel chest	Often (30–79%)
Generalized low muscle tone in neonate	Often (30–79%)
Involuntary muscle stiffness, contraction, or spasm	Often (30–79%)
Muscle degeneration	Often (30–79%)
Polyarticular arthritis	Often (30–79%)
Hunched back	Sometimes (5–29%)
Joint stiffness	Sometimes (5–29%)
Kyphoscoliosis	Sometimes (5–29%)
Low muscle tone, in neonatal onset	Sometimes (5–29%)
Progressive spasticity	Not recorded
Rigidity	Not recorded
Spastic walk	Not recorded

Abnormality of the immune system

Trait	How often it is seen
Severe infection	Always
Antinuclear antibody positivity	Very often (80–99%)
Anti-complement component C1q antibody positivity	Often (30–79%)
Anti-ribosome Po antibody positivity	Often (30–79%)
Anti-titin antibody positivity	Often (30–79%)
Antineutrophil antibody positivity	Often (30–79%)
Decreased circulating complement C3 concentration	Often (30–79%)
Decreased circulating complement C4 concentration	Often (30–79%)
Malar rash	Often (30–79%)
Recurrent infections	Often (30–79%)
Recurrent respiratory infections	Often (30–79%)
Anti-dsDNA antibody positivity	Sometimes (5–29%)
Anti-La/SS-B antibody positivity	Sometimes (5–29%)
Anti-nucleoporin 62 antibody positivity	Sometimes (5–29%)
Anti-phosphatidic acid antibody positivity	Sometimes (5–29%)
Anti-Ro52/TRIM21 antibody positivity	Sometimes (5–29%)
Anti-Sm antibody positivity	Sometimes (5–29%)
Anti-U1 ribonucleoprotein antibody positivity	Sometimes (5–29%)
Discoid lupus rash	Sometimes (5–29%)
Serositis	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Anorexia	Very often (80–99%)
Acid reflux	Often (30–79%)
Chronic constipation	Often (30–79%)
Constipation	Often (30–79%)
Functional abnormality of the gastrointestinal tract	Often (30–79%)
Gastrostomy tube feeding in infancy	Often (30–79%)
Hernia of the abdominal wall	Often (30–79%)
Poor suck	Often (30–79%)
Gallbladder inflammation	Sometimes (5–29%)
Feeding difficulties in infancy	Not recorded
Poor swallowing	Not recorded

Laboratory abnormality

Trait	How often it is seen
Fever	Very often (80–99%)
High urine protein levels	Very often (80–99%)
Blood in urine	Often (30–79%)
High urine neutrophil count	Often (30–79%)
Abnormal CSF pyruvate family amino acid concentration	Sometimes (5–29%)
High blood ammonia levels	Sometimes (5–29%)
Higher than normal levels of lactate in blood	Sometimes (5–29%)
Increased circulating pyruvate concentration	Sometimes (5–29%)
Increased CSF lactate	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Cardiac failure	Often (30–79%)
High blood pressure	Often (30–79%)
Raynaud phenomenon	Often (30–79%)
Stroke	Sometimes (5–29%)
Swollen lymph nodes	Sometimes (5–29%)
Abnormal T-wave	Not recorded
Prolonged QTc interval	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Always
Intermittent overbreathing	Always
Abnormal pattern of respiration	Very often (80–99%)
Respiratory function loss	Very often (80–99%)
Episodic tachypnea	Often (30–79%)
Sudden episodic apnea	Often (30–79%)
Central hypoventilation	Not recorded

Growth abnormality

Trait	How often it is seen
Decreased body weight	Always
Short stature	Very often (80–99%)
Weight loss	Very often (80–99%)
Faltering weight	Often (30–79%)
Growth delay	Often (30–79%)
Obesity	Sometimes (5–29%)
Wasting syndrome	Not recorded

Abnormality of limbs

Trait	How often it is seen
Small hand	Always
Wrist flexion contracture	Always
Short foot	Often (30–79%)
Curvature of little finger	Sometimes (5–29%)
Webbed skin of 2nd-3rd toes	Sometimes (5–29%)
High-arched foot	Not recorded

Abnormality of the eye

Trait	How often it is seen
Drooping upper eyelid	Very often (80–99%)
Juvenile cataract	Often (30–79%)
Noninflammatory retina disease	Rarely (1–4%)
Total ophthalmoplegia	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Hypospadias	Very often (80–99%)
Large testis	Very often (80–99%)
Undescended testes	Very often (80–99%)
Lupus nephritis	Often (30–79%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Decreased blood leukocyte number	Often (30–79%)
Hemolytic anemia	Sometimes (5–29%)
Low platelet count	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Increased serum serotonin	Often (30–79%)
Decreased function of male gonad	Sometimes (5–29%)
Increased serum leptin	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Fatigue	Very often (80–99%)
Malaise	Very often (80–99%)
Coldness	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Large ears	Sometimes (5–29%)
Low-set ears	Not recorded

Abnormality of the integument

Trait	How often it is seen
Hair loss	Often (30–79%)
Photosensitive skin	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Abnormality of chromosome segregation	Very often (80–99%)

Abnormality of the breast

Trait	How often it is seen
Enlarged male breast	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
High-pitched cry	Very often (80–99%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to MECP2 and how often each is seen. Find out more at hpo.jax.org.

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