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Neurodevelopmental disorder with nonspecific brain abnormalities and with or without seizures(NEDBAS)

MedGen UID:
Concept ID:
Disease or Syndrome
Gene (location): DLL1 (6q27)
Monarch Initiative: MONDO:0032877
OMIM®: 618709


Neurodevelopmental disorder with nonspecific brain abnormalities is a highly variable syndrome characterized by impaired intellectual development and behavioral abnormalities associated with structural changes on brain imaging. Some patients have seizures, hypotonia, and scoliosis/kyphosis. Cognitive function ranges from severely impaired to the ability to attend schools with special assistance (summary by Fischer-Zirnsak et al., 2019). [from OMIM]

Clinical features

From HPO
Cerebellar ataxia
MedGen UID:
Concept ID:
Disease or Syndrome
Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).
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Disease or Syndrome
Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.
MedGen UID:
Concept ID:
Sign or Symptom
A seizure is an intermittent abnormality of nervous system physiology characterised by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.
Motor stereotypies
MedGen UID:
Concept ID:
Individual Behavior
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.
Cortical dysplasia
MedGen UID:
Concept ID:
Congenital Abnormality
The presence of developmental dysplasia of the cerebral cortex.
Global developmental delay
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Concept ID:
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.
Autistic behavior
MedGen UID:
Concept ID:
Mental or Behavioral Dysfunction
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.
Attention deficit hyperactivity disorder
MedGen UID:
Concept ID:
Mental or Behavioral Dysfunction
Attention-deficit/hyperactivity disorder (ADHD) is a behavioral disorder that typically begins in childhood and is characterized by a short attention span (inattention), an inability to be calm and stay still (hyperactivity), and poor impulse control (impulsivity). Some people with ADHD have problems with only inattention or with hyperactivity and impulsivity, but most have problems related to all three features.\n\nIn people with ADHD, the characteristic behaviors are frequent and severe enough to interfere with the activities of daily living such as school, work, and relationships with others. Because of an inability to stay focused on tasks, people with inattention may be easily distracted, forgetful, avoid tasks that require sustained attention, have difficulty organizing tasks, or frequently lose items.\n\nHyperactivity is usually shown by frequent movement. Individuals with this feature often fidget or tap their foot when seated, leave their seat when it is inappropriate to do so (such as in the classroom), or talk a lot and interrupt others.\n\nImpulsivity can result in hasty actions without thought for the consequences. Individuals with poor impulse control may have difficulty waiting for their turn, deferring to others, or considering their actions before acting.\n\nMore than two-thirds of all individuals with ADHD have additional conditions, including insomnia, mood or anxiety disorders, learning disorders, or substance use disorders. Affected individuals may also have autism spectrum disorder, which is characterized by impaired communication and social interaction, or Tourette syndrome, which is a disorder characterized by repetitive and involuntary movements or noises called tics.\n\nIn most affected individuals, ADHD continues throughout life, but in about one-third of individuals, signs and symptoms of ADHD go away by adulthood.
Abnormality of neuronal migration
MedGen UID:
Concept ID:
Congenital Abnormality
An abnormality resulting from an anomaly of neuronal migration, i.e., of the process by which neurons travel from their origin to their final position in the brain.
Abnormal corpus callosum morphology
MedGen UID:
Concept ID:
Anatomical Abnormality
Abnormality of the corpus callosum.
MedGen UID:
Concept ID:
An increase in size of the ventricular system of the brain.
Intellectual disability
MedGen UID:
Concept ID:
Mental or Behavioral Dysfunction
Intellectual disability, previously referred to as mental retardation, is characterized by subnormal intellectual functioning that occurs during the developmental period. It is defined by an IQ score below 70.
MedGen UID:
Concept ID:
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.
Abnormal vertebral morphology
MedGen UID:
Concept ID:
Anatomical Abnormality
An abnormality of one or more of the vertebrae.
MedGen UID:
Concept ID:
Occipitofrontal (head) circumference greater than 97th centile compared to appropriate, age matched, sex-matched normal standards. Alternatively, a apparently increased size of the cranium.
MedGen UID:
Concept ID:
Head circumference below 2 standard deviations below the mean for age and gender.
Abnormal facial shape
MedGen UID:
Concept ID:
An abnormal morphology (form) of the face or its components.

Professional guidelines


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Ziobro J, Shellhaas RA
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Recent clinical studies


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Clinical prediction guides

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Recent systematic reviews

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