Last updated:
7/18/2025
Years published: 2009, 2012, 2025
NORD gratefully acknowledges Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, for the preparation of this report.
Pontocerebellar hypoplasias (PCH) are a group of very rare, inherited conditions in which two parts of the brain, the pons and the cerebellum do not develop fully before birth or begin to shrink (atrophy) soon afterward. As a result, children with PCH often have a small head size (microcephaly), problems with vision (optic nerve atrophy), abnormal muscle tone (dystonia), difficulty coordinating movements (ataxia) and other neuromuscular issues.1,2,3
As of 2025, PCH includes about 17 subtypes that are caused by changes (variants) in different genes. Most of these follow an autosomal recessive inheritance pattern, meaning a child must inherit two copies of a gene-causing variant (one copy with the variant from each parent). The genes that cause PCH are involved in several cellular processes but because each gene has a slightly different function, the exact symptoms and severity can vary from one PCH subtype to another.1,2 The better outcomes have been seen in people with late-onset PCH 1 and a few people with PCH 2A.
Diagnosis is based on signs and symptoms, imaging exams, electrodiagnostic studies such as electromyography and nerve conduction tests and it is confirmed by genetic testing.
There is currently no cure for PCH. Care focuses on managing symptoms and maximizing quality of life.1
pontocerebellar hypoplasia, type 1A
pontocerebellar hypoplasia, type 1B
pontocerebellar hypoplasia, type 1C
ppntocerebellar hypoplasia, type 1D
pontocerebellar hypoplasia, type 1E
pontocerebellar hypoplasia, type 1F
pontocerebellar hypoplasia, type 2A
pontocerebellar hypoplasia, type 2B
pontocerebellar hypoplasia, type 2C
pontocerebellar hypoplasia, type 2D
pontocerebellar hypoplasia, type 2E
pontocerebellar hypoplasia, type 2F
pontocerebellar hypoplasia, type 3
pontocerebellar hypoplasia, type 4
pontocerebellar hypoplasia, type 5
pontocerebellar hypoplasia, type 6
pontocerebellar hypoplasia, type 7
pontocerebellar hypoplasia, type 8
pontocerebellar hypoplasia, type 9
pontocerebellar hypoplasia, type 10
pontocerebellar hypoplasia, type 11
pontocerebellar hypoplasia, type 12
pontocerebellar hypoplasia, type 13
pontocerebellar hypoplasia, type 14
pontocerebellar hypoplasia, type 15
pontocerebellar hypoplasia, type 16
pontocerebellar hypoplasia, type 17
There are about 17 different subtypes of pontocerebellar hypoplasia (PCH), each caused by a variants in different genes.1, 3,4,5,6
PCH type 1 (subtypes 1A through 1F)
Babies with PCH type 1 are often described as “floppy babies” at birth because their muscles are very weak and lack normal tone. From the first days of life, they struggle to hold up their head or move their arms and legs. Sucking and swallowing can be so difficult that feeding by mouth may be impossible and breathing can become unreliable, leading to repeated lung infections. On brain scans, the parts called the pons and the cerebellum are underdeveloped and the spinal nerves that control movement show loss of the large motor cells, much like spinal muscular atrophy. Many children develop a very small head, called microcephaly, and have damage to the optic nerve, the nerve of the eye that transmits signals for vision. Learning and thinking are severely affected and most children with PCH type 1 do not survive past early childhood.
In contrast, a few people whose PCH shows up later, mainly as muscle weakness or nerve trouble in the arms and legs, tend to have a milder course. They can often walk, talk and manage daily activities for many years, sometimes decades, especially with physical therapy, braces or mobility aids and regular follow-up with neurology and rehabilitation specialists.
In general, early onset of PCH is typically associated with a more severe disorder, especially when associated with neurodevelopmental abnormalities. Later onset may be associated with slowly progressive milder manifestations, even in the presence of some neurodevelopmental abnormalities.
PCH1A
This form of pontocerebellar hypoplasia (PCH1A) is present before birth or becomes noticeable right after a baby is born. Children with PCH1A often have a very small head (microcephaly) and struggle to breathe on their own. Their muscles are unusually tight or stiff, leading to joint contractures (joints that don’t move normally), deformed feet, general muscle weakness, twitching under the skin and low muscle tone (hypotonia). As they grow, these children usually have delays in reaching motor and thinking milestones and may have trouble with coordination (ataxia) and over-active reflexes. Death in childhood may occur.
PCH1B
Newborns with pontocerebellar hypoplasia type 1B (PCH1B) present with skeletal muscle weakness that manifests as hypotonia (sometimes with congenital joint contractures) and poor feeding. If they survive, they will likely have spasticity, dystonia and seizures. Within the first year of life, respiratory insufficiency and swallowing difficulties are common. Intellectual disability is severe. Life expectancy ranges from a few weeks to adolescence. Because PCH1B is caused by EXOSC3 gene variants, it is classified under EXOSC3-PCH. To date, 82 individuals (from 58 families) with EXOSC3-PCH have been described.7
PCH1C
Pontocerebellar hypoplasia type 1C is characterized by severe muscle weakness and failure to thrive in the first months of life. Affected infants show delayed psychomotor development, often with visual and hearing impairment and may die of respiratory failure. Brain imaging typically shows a small cerebellum (the part of the brain that is responsible for movement control) and small corpus callosum (the brain structure that connects the two halves (hemispheres) of the brain, cerebellar hypoplasia and immature myelination. Myelination is the process of forming a myelin sheath, a fatty insulation layer around nerve fibers (axons) in the nervous system. This sheath is crucial for rapid and efficient nerve impulse transmission, allowing for faster and more effective communication between different parts of the body and the brain.8
PCH1D
Pontocerebellar hypoplasia type 1D (PCH1D) is characterized by severe hypotonia (low muscle tone) and a condition where there is damage to motor nerves which carry signals from the brain to muscles, leading to muscle weakness and thinning (atrophy) known as motor neuronopathy. These symptoms are apparent at birth or in infancy. Affected people have respiratory insufficiency, feeding difficulties and severely delayed or minimal gross motor development. Other features may include eye movement abnormalities, poor overall growth and contractures.9
PCH1E
Babies born with PCH1E have a recognizable facial appearance (eyes that tend to drift outward (exotropia), a narrow space between the temples, an upturned nose with a rounded tip, a tent-shaped upper lip, a narrow roof of the mouth and a flatter middle face). Over time, there is damage to the optic nerve (optic atrophy), involuntary eye movements (nystagmus) and progressive vision loss. Breathing difficulties are common. Other symptoms may include a curved spine (scoliosis), high-arched feet (pes cavus), stiff joints, weak and less active muscles, slurred speech (dysarthria), shrinking of nerve-connected muscle fibers (neurogenic atrophy) and tapering of the fingers. Other problems include delayed development, limited spontaneous movement, inability to reach typical milestones, shaky walking (ataxic gait), seizures and a loss of sensation and movement in peripheral nerves (sensorimotor neuropathy).
PCH1F
Pontocerebellar hypoplasia type 1F (PCH1F) is characterized by hypotonia, global developmental delay, poor overall growth and distinctive facial features. Brain imaging shows pontocerebellar hypoplasia, thin corpus callosum, cerebral atrophy and delayed myelination.
PCH type 2 (subtypes 2A through 2F)
In PCH type 2 the main characteristic is an early movement disorder which includes involuntary twisting, jerking or writhing of the limbs, known as dystonia and choreoathetoid movements, beginning in the first weeks of life. Although muscle tone is low in the trunk, these involuntary contractions can make some limbs stiff. Babies have very poor head control, cannot sit or feed without help and often breathe irregularly. Swallowing difficulty raises the risk of food or liquid entering the lungs, causing pneumonia. Many children have seizures, develop microcephaly and have trouble tracking objects with their eyes. Most affected children do not survive beyond the first year. However, new reports indicate that PCH type 2A is characterized by an early onset degeneration which thereafter stabilizes.4 The severity of symptoms varied but most of these children face a serious, life-shortening condition, with many not living past their early teens. Despite these problems, around two-thirds of the children achieved some gains in thinking and movement skills over time. Interestingly, whether a child showed symptoms before birth did not predict how they would do later on. This gives hope that early prenatal signs need not determine a child’s long-term potential.
PCH type 3
Children with PCH type 3 have floppy muscles in the body with unusually stiff arms and legs as well as severe developmental delay and never reaching milestones such as sitting or speaking. They also have microcephaly and many have seizures; a few also have hearing loss. Because only a few families have been described worldwide, doctors continue to learn about the outcome.
PCH type 4
PCH type 4 is one of the most severe forms. Symptoms are evident before birth. Imaging often shows a very poor development of the pons or cerebellum and prenatal ultrasound may reveal tight joints or breathing pauses in the womb. Infants with this type are usually stillborn or die within days of birth. A stillbirth is when a fetus dies in the uterus after 20 weeks of pregnancy. Because it is caused by TSEN54 gene variants it is classified as a TSEN54‐related subtype.10
PCH type 5
In PCH5, also caused by TSEN54 gene variants,10 the damage starts before birth, causing microcephaly detectable on prenatal ultrasound and often accompanied by excess amniotic fluid. Babies are born with stiff joints and severe cerebellar and brain-stem underdevelopment. They have little or no spontaneous movement, profound feeding and breathing difficulties and typically do not survive beyond the neonatal period. As of 2024, one family has been reported.
PCH type 6
PCH6 is characterized by a distinct facial appearance, a narrow, pinched face with deep‐set eyes and a high nasal bridge. From birth, there is progressive microcephaly, periods of breathing pauses (apnea), poor feeding and swelling of the hands and feet. Muscle tone may be low, yet some contractures occur. Development is profoundly delayed, seizures frequently disrupt sleep and blood or spinal fluid shows elevated lactic acid, evidence of a mitochondrial energy deficit. Imaging demonstrates both cerebellar and brainstem atrophy. Most children do not reach early milestones and have a shortened life span. Some children survive into later childhood when given supportive therapies for breathing, feeding and physical function
PCH type 6
Newborns with PCH type 6 appear very floppy and may have seizures early on. Over time they develop signs of peripheral neuropathy, which means the nerves outside the brain and spinal cord become damaged, causing weakness, numbness or tingling in the arms and legs. Many children also show involuntary eye movements or struggle to move their eyes smoothly. Some children survive into later childhood when given supportive therapies for breathing, feeding and physical function.
PCH type 7
Newborns with PCH type 7 appear very floppy, similarly, to type 1, but there is a highly distinctive feature in males in which there is ambiguous or underdeveloped genitalia, sometimes called a disorder of sex development. There are elevated baseline of the LH/FSH (gonadotropins) which are hormones that regulate the function of the ovaries and testes (gonads). Infants still struggle with muscle weakness, feeding and breathing, but the genital findings are what set this subtype apart. Because fewer than ten families have been reported, the outcome is not known.
PCH type 8
PCH type 8 is an extremely rare form and babies present with profound hypotonia (very low muscle tone) and almost no purposeful movement. Some babies show stiffness in certain limbs and may have vision problems such as involuntary eye movements or optic nerve damage. Only about three families in the world are known.
PCH type 9
Children with PCH type 9 develop severe muscle weakness and breathing or feeding distress almost immediately after birth. Children show a loss of the skills they have gained, and brain scans reveal ongoing shrinkage of the most important brain structures. This form progresses rapidly, and most infants do not survive beyond the first months.
PCH type 10
Children with PCH type 10 have global developmental delay from infancy and are unable to hold up their head, cannot sit or babble and often never speak. Many children develop increased muscle stiffness (spasticity) and may have seizures. Subtle facial anomalies have been noted in a few reported people. Lifespan is generally limited without full respiratory and feeding support.
PCH type 11
Babies with PCH type 11 are floppy and feed poorly in the first months. As they grow, some develop episodes of ataxia, meaning they lose balance and coordination, leading to unsteady movement or tremor. Learning and thinking skills range from moderately to severely affected. So far, only a small number of affected children have been reported.
PCH type 12
Babies with PCH type 12 have the usual low muscle tone and feeding difficulties. The most distinctive sign is ocular motor apraxia in which the eyes cannot move on command, making it hard to shift gaze or follow objects. Later in childhood many develop peripheral nerve problems, causing numbness or weakness in the limbs. As more children are diagnosed in the future, other signs and symptoms may be known.
PCH type 13
Babies with PCH13 have microcephaly, brachycephaly and distinctive facial features such as reduced facial tone (hypotonic facies), full cheeks, a short groove between nose and lip, overfolded ears, epicanthal folds, strabismus, eyelid drooping (ptosis), long eyelashes, nystagmus, wide-spaced eyes (hypertelorism), an upturned nasal tip, a thin upper lip with a thickened red border and narrow, high-arched palates. There are visual problems and dental caries.
Respiratory issues include recurrent infections, sleep apnea and asthma. Gastrointestinal problems range from feeding difficulties and constipation to cholestatic hepatitis (bile-stasis liver injury) with enlarged liver (hepatomegaly) and liver problems. Muscular hypotonia, lower-extremity edema and flat feet (pes planus) occur. Children show global developmental delay, impaired cognition, absence of speech, inability to sit or walk, delayed walking, an unsteady ataxic gait and seizures. Failure to thrive and poor overall growth are also present.
PCH type 14
Children with PCH14 have very poor or absent psychomotor development, meaning they fail to achieve milestones such as grasping, rolling or sitting, and impaired intellectual development, indicating global cognitive delay, as well as hypotonia, spastic quadriplegia, which is an increased muscle stiffness in all four limbs due to upper motor neuron injury, brisk reflexes (overactive stretch reflexes such as an exaggerated knee‐jerk) involuntary muscle contractions that produce twisting movements or abnormal postures and seizures, defined as recurrent, unprovoked episodes of abnormal electrical activity in the brain. Most children with PCH14 die in early infancy or childhood due to the combination of severe neurologic impairment and brainstem dysfunction.
PCH type 15
Infants with PCH type 15 have low muscle tone, involuntary twisting or stiff movements and early signs of coordination problems. Over time they lose vision as the optic nerves deteriorate. Cognitive delay is typically mild to moderate. Only a few families are known, so the outcome is not known.
PCH type 16
Newborns with PCH type 16 have a head circumference that falls increasingly behind normal growth curves (progressive microcephaly), a small, receding jaw (micrognathia), low-set ears and a prominent nasal bridge. Eye problems include repetitive involuntary eye movements (nystagmus), drooping eyelids (ptosis), degeneration of the optic nerve (optic atrophy), cataracts, abnormal eye movements and cortical blindness.
These babies have eating difficulties, often necessitating tube feeding. A sideways curvature of the spine (scoliosis) may be present. Neurologically, these babies never attain developmental milestones, lack head control, cannot sit or walk, show profoundly delayed motor and intellectual progress and do not learn to talk. They also show reduced trunk muscle tone (axial hypotonia) alongside increased tone in the limbs, stiffness in all four limbs (spastic tetraplegia), repetitive, purposeless motions (stereotypic movements), movement abnormalities from basal-ganglia involvement (extrapyramidal signs), incoordination (ataxia), limb stiffness and seizures.
PCH type 17
PCH17 presents in utero with microcephaly, facial differences, eye abnormalities and cleft palate. Respiratory insufficiency, apneic pauses and hypoventilation occur. Feeding and swallowing difficulties often require tube support. Neurologic features include neonatal hypotonia, absence of developmental progress, global developmental delay, intellectual impairment, distal limb hypertonia, spastic tetraplegia, seizures and lack of involuntary body functions (autonomic dysfunction). Brain MRI reveals cerebellar and brainstem hypoplasia. Hypoglycemia is the main biochemical abnormality and affected infants show poor growth, slow heart rate (bradycardia) and hypertension.
Pontocerebellar hypoplasia (PCH) includes a group of autosomal-recessive neurodegenerative disorders marked by early underdevelopment and progressive atrophy of the cerebellum and pons. The currently known 17 subtypes are caused by variants in different genes.
The specific PCH subtypes and their causative genes are:
Recessive genetic disorders occur when an individual inherits a disease-causing gene variant from each parent. If an individual receives one normal gene and one disease-causing gene variant, the person will be a carrier for the disease but usually will not show symptoms. The risk for two carrier parents to both pass the gene variant and have an affected child is 25% with each pregnancy. The risk of having a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents is 25%. The risk is the same for males and females.
The overall incidence and prevalence of PCH are unknown. The incidence of one of the more frequent variants, PCH2A, has been estimated at less than 1 in 200,000.4
Diagnosing PCH typically involves a combination of:1,2,3
Treatment
There is currently no cure for PCH. Care focuses on managing symptoms and maximizing quality of life:1,2,3
Supportive therapies include physical, occupational and speech therapy to maintain joint mobility, improve feeding and communication and encourage whatever motor skills are possible.
Nutritional support with special feeding techniques or supplemental nutrition can help to ensure adequate growth.
Respiratory care, including monitoring for breathing difficulties is needed and some children may require assisted ventilation.
Seizure management includes anticonvulsant medications.
In the most severely affected patients, palliative care is crucial. It is important to support the family and to address any other symptoms like pain and behavioral problems.
Because PCH can range from forms that are fatal in the newborn period to very mild, later-onset types (some affected people living into adulthood with primarily neuromuscular symptoms), treatment plans are highly individualized and adjusted over time.3,4,5
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Tollfree: (800) 411-1222
TTY: (866) 411-1010
Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website: https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact: www.centerwatch.com
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
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NORD and MedicAlert Foundation have teamed up on a new program to provide protection to rare disease patients in emergency situations.
Learn more https://rarediseases.org/patient-assistance-programs/medicalert-assistance-program/Ensuring that patients and caregivers are armed with the tools they need to live their best lives while managing their rare condition is a vital part of NORD’s mission.
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Learn more https://rarediseases.org/patient-assistance-programs/caregiver-respite/The information provided on this page is for informational purposes only. The National Organization for Rare Disorders (NORD) does not endorse the information presented. The content has been gathered in partnership with the MONDO Disease Ontology. Please consult with a healthcare professional for medical advice and treatment.
The Genetic and Rare Diseases Information Center (GARD) has information and resources for patients, caregivers, and families that may be helpful before and after diagnosis of this condition. GARD is a program of the National Center for Advancing Translational Sciences (NCATS), part of the National Institutes of Health (NIH).
View reportOrphanet has a summary about this condition that may include information on the diagnosis, care, and treatment as well as other resources. Some of the information and resources are available in languages other than English. The summary may include medical terms, so we encourage you to share and discuss this information with your doctor. Orphanet is the French National Institute for Health and Medical Research and the Health Programme of the European Union.
View reportOnline Mendelian Inheritance In Man (OMIM) has a summary of published research about this condition and includes references from the medical literature. The summary contains medical and scientific terms, so we encourage you to share and discuss this information with your doctor. OMIM is authored and edited at the McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine.
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