Developmental and epileptic encephalopathy 68

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE68 is an autosomal recessive form characterized by onset of twitching and/or myoclonic jerks in infancy. The disorder progresses to refractory generalized tonic-clonic seizures, often resulting in status epilepticus, loss of developmental milestones, and early death. Other features include delayed development, axial hypotonia, spasticity of the limbs, and clonus.

Developmental and epileptic encephalopathy 45

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent.

Developmental and epileptic encephalopathy 100

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE100 is an autosomal dominant, severe form characterized by global developmental delay and onset of variable types of seizures in the first months or years of life.

Rett syndrome congenital variant

A severe neurodevelopmental disorder with features of classic Rett syndrome but earlier onset in the first months of life. Clinical features include progressive microcephaly, hypotonia, irresponsiveness and irritability in the neonatal period, intellectual disability, psychomotor regression and stereotypical movements.

Congenital disorder of glycosylation 1AA

A form of congenital disorder of glycosylation, a multisystem disorder caused by a defect in glycoprotein biosynthesis and characterized by under-glycosylated serum glycoproteins. Congenital disorders of glycosylation result in a wide variety of clinical features, such as defects in the nervous system development, psychomotor retardation, dysmorphic features, hypotonia, coagulation disorders, and immunodeficiency. The broad spectrum of features reflects the critical role of N-glycoproteins during embryonic development, differentiation, and maintenance of cell functions. CDG1AA inheritance is autosomal recessive.

Cognitive impairment with or without cerebellar ataxia

A disorder characterized by markedly delayed cognitive and motor development, attention deficit disorder, and cerebellar ataxia. Features include bilateral esophoria, strabismatic amblyopia, unsustained gaze evoked nystagmus on horizontal gaze, ataxic gait, dysmetria in the upper limbs and dysarthria, with normal strength, tone, and reflexes.

Developmental and epileptic encephalopathy 102

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE102 is an autosomal recessive form characterized by onset of variable types of seizures in infancy.

Developmental and epileptic encephalopathy 65

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE65 is an autosomal dominant form characterized by onset of intractable seizures usually in the first 6 months of life and severe to profound psychomotor developmental delay.

Migraine, familial hemiplegic, 2

A subtype of migraine with aura associated with hemiparesis in some families. Migraine is a disabling symptom complex of periodic headaches, usually temporal and unilateral. Headaches are often accompanied by irritability, nausea, vomiting and photophobia, preceded by constriction of the cranial arteries. Migraine with aura is characterized by recurrent attacks of reversible neurological symptoms (aura) that precede or accompany the headache. Aura may include a combination of sensory disturbances, such as blurred vision, hallucinations, vertigo, numbness and difficulty in concentrating and speaking.

Developmental and epileptic encephalopathy 25, with amelogenesis imperfecta

An autosomal recessive disease characterized by subclinical seizures appearing in the first days of life, evolving to severe epileptic disease. Affected individuals have profound or severe delayed development with lack of speech, and most patients do not acquire the ability to sit. Additional variable features include axial hypotonia, peripheral hypertonia, and abnormal involuntary movements such as dystonia and choreoathetosis. Dental abnormalities, including delayed eruption, hypodontia, tooth hypoplasia, yellow discoloration, thin enamel, and enamel chipping are observed in most patients.

Developmental and epileptic encephalopathy 76

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE76 is an autosomal recessive form that may result in death in childhood.

Retinitis pigmentosa 59

A retinal dystrophy belonging to the group of pigmentary retinopathies. Retinitis pigmentosa is characterized by retinal pigment deposits visible on fundus examination and primary loss of rod photoreceptor cells followed by secondary loss of cone photoreceptors. Patients typically have night vision blindness and loss of midperipheral visual field. As their condition progresses, they lose their far peripheral visual field and eventually central vision as well.

Cutis laxa, autosomal recessive, 2D

A form of cutis laxa, a disorder characterized by an excessive congenital skin wrinkling, a large fontanelle with delayed closure, a typical facial appearance with downslanting palpebral fissures, and a general connective tissue weakness. Most ARCL2D patients exhibit severe hypotonia as well as cardiovascular and neurologic involvement.

Developmental and epileptic encephalopathy 48

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE48 is an autosomal recessive form characterized by onset of seizures in the first year of life. Affected individuals manifest global developmental delay, intellectual disability, absent speech, and poor, if any, motor development.

Developmental and epileptic encephalopathy 26

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE26 patients manifest multiple types of seizures, delayed psychomotor development, poor or absent speech, hypotonia, hypsarrhythmia.

Intellectual developmental disorder, X-linked, syndromic, Houge type

A disorder characterized by delayed development, intellectual disability, speech and language delay, and early-onset seizures. Carrier females may be mildly affected.

Parkinson disease 20, early-onset

An early-onset form of Parkinson disease, a complex neurodegenerative disorder characterized by bradykinesia, resting tremor, muscular rigidity and postural instability, as well as by a clinically significant response to treatment with levodopa. The pathology involves the loss of dopaminergic neurons in the substantia nigra and the presence of Lewy bodies (intraneuronal accumulations of aggregated proteins), in surviving neurons in various areas of the brain. PARK20 is characterized by young adult-onset of parkinsonism. Additional features may include seizures, cognitive decline, abnormal eye movements, and dystonia.

Developmental and epileptic encephalopathy 47

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent.

Developmental and epileptic encephalopathy 44

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE44 transmission pattern is consistent with autosomal recessive inheritance.

Developmental and epileptic encephalopathy 86

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE86 inheritance is autosomal recessive.

Epilepsy, familial focal, with variable foci 4

An autosomal dominant form of epilepsy characterized by focal seizures arising from different cortical regions, including the temporal, frontal, parietal, and occipital lobes. Seizure types commonly include temporal lobe epilepsy, frontal lobe epilepsy, and nocturnal frontal lobe epilepsy. Some patients may have intellectual disability or autism spectrum disorders. Seizure onset usually occurs in the first or second decades, although later onset has been reported, and there is phenotypic variability within families. A subset of patients have structural brain abnormalities. Penetrance of the disorder is incomplete. FFEVF4 is characterized by onset of focal seizures in the first years of life.

Developmental and epileptic encephalopathy 66

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE66 is an autosomal dominant form characterized by onset of seizures in first days or weeks of life.

Developmental and epileptic encephalopathy 21

A severe disease characterized by intractable seizures, profound global developmental delay, and persistent severe axial hypotonia as well as appendicular hypertonia.

Epileptic encephalopathy, infantile or early childhood, 2

A form of epileptic encephalopathy, a heterogeneous group of severe childhood onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. IECEE2 is an autosomal dominant condition with variable age at seizure onset, ranging from early infancy to 6 years.

Developmental and epileptic encephalopathy 46

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent.

Developmental and epileptic encephalopathy 58

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE58 is an autosomal dominant condition characterized by onset of refractory seizures in the first days or months of life.

Developmental and epileptic encephalopathy 109

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE109 is an autosomal dominant form characterized by the onset of various types of seizures in the first months or years of life.

Developmental and epileptic encephalopathy 24

A disease characterized by early-onset seizures, intellectual disability of varying degrees, and behavioral disturbances or autistic features in most individuals.

Developmental and epileptic encephalopathy 79

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE79 is an autosomal dominant form characterized by onset of refractory seizures in the first months of life. Brain imaging may show hypomyelination, cerebral atrophy and thinning of the corpus callosum.

Neurodevelopmental disorder with poor language and loss of hand skills

An autosomal dominant disorder characterized by psychomotor developmental stagnation or regression. NDPLHS manifest in the first years of life as loss of purposeful hand movements, loss of language, and intellectual disability.

Beukes hip dysplasia

A severe progressive degenerative osteoarthritis of the hip joint with underlying dysplasia confined to that region. Affected individuals are of normal stature and have no associated health problems. Inheritance is autosomal dominant.

Developmental and epileptic encephalopathy 41

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE41 inheritance is autosomal dominant.

Developmental and epileptic encephalopathy 31A

An autosomal dominant epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent.

Epileptic encephalopathy, infantile or early childhood, 1

A form of epileptic encephalopathy, a heterogeneous group of severe childhood onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. IECEE1 is an autosomal dominant condition with onset of seizures between the first weeks and first years of life.

Dystonia 12

An autosomal dominant dystonia-parkinsonism disorder. Dystonia is defined by the presence of sustained involuntary muscle contractions, often leading to abnormal postures. DYT12 patients develop dystonia and parkinsonism between 15 and 45 years of age. The disease is characterized by an unusually rapid evolution of signs and symptoms. The sudden onset of symptoms over hours to a few weeks, often associated with physical or emotional stress, suggests a trigger initiating a nervous system insult resulting in permanent neurologic disability.

Developmental and epileptic encephalopathy 78

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE78 is an autosomal dominant form characterized by onset of refractory seizures in the first days or months of life. Clinical features include severe developmental delay, hypotonia, microcephaly, cortical visual impairment and profound intellectual disability. Some patients manifest a less severe phenotype characterized by pharmacoresponsive epilepsy, autism spectrum disorder and moderate intellectual disability.

Developmental and epileptic encephalopathy 97

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE97 is an autosomal dominant form.

Charcot-Marie-Tooth disease, axonal, type 2N

An axonal form of Charcot-Marie-Tooth disease, a disorder of the peripheral nervous system, characterized by progressive weakness and atrophy, initially of the peroneal muscles and later of the distal muscles of the arms. Charcot-Marie-Tooth disease is classified in two main groups on the basis of electrophysiologic properties and histopathology: primary peripheral demyelinating neuropathies (designated CMT1 when they are dominantly inherited) and primary peripheral axonal neuropathies (CMT2). Neuropathies of the CMT2 group are characterized by signs of axonal degeneration in the absence of obvious myelin alterations, normal or slightly reduced nerve conduction velocities, and progressive distal muscle weakness and atrophy.

Developmental and epileptic encephalopathy 18

A severe autosomal recessive neurologic disorder characterized by lack of psychomotor development apparent from birth, dysmorphic facial features, early onset of refractory seizures, and thick corpus callosum and persistent cavum septum pellucidum on brain imaging.

Developmental and epileptic encephalopathy 56

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE56 is an autosomal dominant condition.

Spinocerebellar ataxia 6

Spinocerebellar ataxia is a clinically and genetically heterogeneous group of cerebellar disorders. Patients show progressive incoordination of gait and often poor coordination of hands, speech and eye movements, due to degeneration of the cerebellum with variable involvement of the brainstem and spinal cord. SCA6 is an autosomal dominant cerebellar ataxia (ADCA), mainly caused by expansion of a CAG repeat in the coding region of CACNA1A. There seems to be a correlation between the repeat number and earlier onset of the disorder.

Neurodevelopmental disorder with seizures and non-epileptic hyperkinetic movements

An autosomal recessive, complex and progressive neurologic disorder characterized by severe neurodevelopmental delay and developmental regression, epileptic encephalopathy, postnatal microcephaly, hypotonia, and non-epileptic hyperkinetic movement disorder, including myoclonus dystonia, choreoathetosis, or generalized dyskinesia. Disease onset in infancy or first years of life.

Developmental and epileptic encephalopathy 33

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent.

Developmental and epileptic encephalopathy 32

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE32 inheritance is autosomal dominant.

Developmental and epileptic encephalopathy 112

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE112 is an autosomal dominant form characterized by onset in infancy, and a wide range of seizure types including focal and generalized seizures. Cognitive outcomes range from normal intellect to profound intellectual development impairment.

Developmental and epileptic encephalopathy 87

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE87 inheritance is autosomal dominant.

Generalized epilepsy with febrile seizures plus 2

A rare autosomal dominant, familial condition with incomplete penetrance and large intrafamilial variability. Patients display febrile seizures persisting sometimes beyond the age of 6 years and/or a variety of afebrile seizure types. This disease combines febrile seizures, generalized seizures often precipitated by fever at age 6 years or more, and partial seizures, with a variable degree of severity.

Intellectual developmental disorder, autosomal dominant 5

A disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period. MRD5 patients show global developmental delay with delayed motor development, hypotonia, moderate-to-severe intellectual disability, and severe language impairment. Epilepsy and autism can be present in some patients.

Developmental and epileptic encephalopathy 74

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE74 is an autosomal dominant form with onset in the first year of life.

Epilepsy, familial focal, with variable foci 1

An autosomal dominant form of epilepsy characterized by focal seizures arising from different cortical regions in different family members. Many patients have an aura and show automatisms during the seizures, whereas others may have nocturnal seizures. There is often secondary generalization. Some patients show abnormal interictal EEG, and some patients may have intellectual disability or autism spectrum disorders. Seizure onset usually occurs in the first or second decades, although later onset has been reported, and there is phenotypic variability within families. Penetrance of the disorder is incomplete.

Developmental and epileptic encephalopathy 75

A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE75 is an autosomal recessive form characterized by onset of severe refractory seizures in the first months of life.

Developmental and epileptic encephalopathy 110

A form of epileptic encephalopathy, a heterogeneous group of early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE110 is an autosomal recessive form characterized by profound global developmental delay and hypotonia apparent in infancy followed by onset of seizures in the first months or years of life.

Intellectual developmental disorder, autosomal dominant 56

A form of intellectual disability, a disorder characterized by significantly below average general intellectual functioning associated with impairments in adaptive behavior and manifested during the developmental period.