The combination of muscular hypotonia and fixed dilated pupils in infancy is suspicious of Gillespie syndrome. Early onset partial aniridia, cerebellar ataxia, and mental retardation are hallmark of syndrome. The iris abnormality is specific and seems pathognomonic of Gillespie syndrome. The aniridia consisting of a superior coloboma and inferior iris hypoplasia, foveomacular dysplasia.

Atypical Gillespie syndrome associated with bilateral ptosis, exotropia, correctopia, iris hypoplasia, anterior capsular lens opacities, foveal hypoplasia, retinal vascular tortuosity, and retinal hypopigmentation.

Neurological signs ar nystagmus, mild craniofacial asymmetry, axial hypotonia, developmental delay, and mild mental retardation. Mariën P did not support the prevailing view of a global mental retardation as a cardinal feature of Gillespie syndrome but primarily reflect cerebellar induced neurobehavioral dysfunctions following disruption of the cerebrocerebellar anatomical circuitry that closely resembles the "cerebellar cognitive and affective syndrome" (CeCAS).

Congenital pulmonary stenosis and helix dysplasia can be associated.

Autosomal recessive cerebellar ataxia type 1 (ARCA1) is a condition characterized by progressive problems with movement. Signs and symptoms of the disorder first appear in early to mid-adulthood. People with this condition initially experience impaired speech (dysarthria), problems with coordination and balance (ataxia), or both. They may also have difficulty with movements that involve judging distance or scale (dysmetria). Other features of ARCA1 include abnormal eye movements (nystagmus) and problems following the movements of objects with their eyes. The movement problems are slowly progressive, often resulting in the need for a cane, walker, or wheelchair.

Most cases of autosomal recessive cerebellar ataxia are early onset, usually around the age of 20. People with this type of ataxia share many characteristic symptoms including:

- frequent falls due to poor balance

- imprecise hand coordination

- postural or kinetic tremor of extremities or trunk

- dysarthria

- dysphasia

- vertigo

- diplopia

- lower extremity tendon reflexes

- dysmetria

- minor abnormalities in ocular saccades

- attention defects

- impaired verbal working memory and visuospatial skills

- Normal life expectancy

Autosomal recessive ataxias are generally associated with a loss of proprioception and vibration sense. Arreflexia is more common in autosomal recessive ataxia than autosomal dominant ataxias. Also, they tend to have more involvement outside of the nervous system. Mutations in subunit of the mitochondrial DNA polymerase (POLG) have been found to be a potential cause of autosomal recessive cerebellar ataxia.

Onset : Early childhood

Progression: Chronic progressive

Clinical: Cerebellar ataxia plus syndrome / Optic Atrophy Plus Syndrome

Ocular: Optic atrophy, nystagmus, scotoma, and bilateral retrobulbar neuritis.

Other: Mental retardation, myoclonic epilepsy, spasticity, and posterior column sensory loss. Tremor in some cases.

Musculoskeletal

Contractures, lower limbs, Achilles tendon contractures, Hamstring contractures, Adductor longus contractures

Systemic

Hypogonadotrophic hypogonadism.

Pontocerebellar hypoplasia is classified as follows:

Pontine and cerebellar hypoplasia is also observed in certain phenotypes of X-linked mental retardation – so called MICPCH.

Individuals with KSS present initially in a similar way to those with typical CPEO. Onset is in the first and second decades of life.

The first symptom of this disease is a unilateral ptosis, or difficulty opening the eyelids, that gradually progresses to a bilateral ptosis. As the ptosis worsens, the individual commonly extends their neck, elevating their chin in an attempt to prevent the eyelids from occluding the visual axis. Along with the insidious development of ptosis, eye movements eventually become limited causing a person to rely more on turning the head side to side or up and down to view objects in the peripheral visual field.

Non-progressive congenital ataxia (NPCA) is a non-progressive form of cerebellar ataxia which can occur with or without cerebellar hypoplasia.

Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare neurodegenerative disorders caused by genetic mutations and characterised by progressive atrophy of various parts of the brain such as the cerebellum or brainstem (particularly the pons). Where known, these disorders are inherited in an autosomal recessive fashion. There is no known cure for PCH.

Behr syndrome is characterized by the association of early-onset optic atrophy with spinocerebellar degeneration resulting in ataxia, pyramidal signs, peripheral neuropathy and developmental delay.

Although it is an autosomal recessive disorder, heterozygotes may still manifest much attenuated symptoms. Autosomal dominant inheritance also being reported in a family. Recently a variant of OPA1 mutation with phenotypic presentation like Behr syndrome is also described. Some reported cases have been found to carry mutations in the OPA1, OPA3 or C12ORF65 genes which are known causes of pure optic atrophy or optic atrophy complicated by movement disorder.

ARSACS is usually diagnosed in early childhood, approximately 12–24 months of age when a child begins to take their first steps. At this time it manifests as a lack of coordination and balance resulting in frequent falls. Some of the signs and symptoms include:

- Stiffness of the legs

- Appendicular and trunk ataxia

- Hollow foot and hand deformities

- Ataxic dysarthria

- Distal muscle wasting

- Horizontal gaze nystagmus

- Spasticity

This syndrome consists a number of typical features. These include

- Agenesis of the corpus callosum (80-99% patients)

- Hypopigmentation of the eyes and hair (80-99% patients)

- Cardiomyopathy (80-99% patients)

- Combined immunodeficiency (80-99% patients)

- Muscular hypotonia (80-99% patients)

- Abnormality of retinal pigmentation (80-99% patients)

- Recurrent chest infections (80-99% patients)

- Abnormal EEG (80-99% patients)

- Intellectual disability (80-99% patients)

- Cataracts (75%)

- Seizures (65%)

- Renal abnormalities (15%)

Infections of the gastrointestinal and urinary tracts are common. Swallowing and feeding difficulties early on may result in a failure to thrive. Optic nerve hypoplasia, nystagmus and photophobia may occur. Facial dysmorphism (cleft lip/palate and micrognathia) and syndactyly may be present. Sensorineural hearing loss may also be present.

Death in infancy is not uncommon and is usually due to cardiac complications or severe infections.

Gillespie syndrome, also called aniridia, cerebellar ataxia and mental deficiency. is a rare genetic disorder. The disorder is characterized by partial aniridia (meaning that part of the iris is missing), ataxia (motor and coordination problems), and, in most cases, intellectual disability. It is heterogeneous, inherited in either an autosomal dominant or autosomal recessive manner. Gillespie syndrome was first described by American ophthalmologist Fredrick Gillespie in 1965.

Symptoms typically are onset in the adult years, although, childhood cases have also been observed. Common symptoms include a loss of coordination which is often seen in walking, and slurred speech. ADCA primarily affects the cerebellum, as well as, the spinal cord. Some signs and symptoms are:

KSS results in a pigmentation of the retina, primarily in the posterior fundus. The appearance is described as a "salt-and-pepper" appearance. There is diffuse depigmentation of the retinal pigment epithelium with the greatest effect occurring at the macula. This is in contrast to retinitis pigmentosa where the pigmentation is peripheral. The appearance of the retina in KSS is similar to that seen in myotonic dystrophy type 1 (abbreviated DM1). Modest night-blindness can be seen in patients with KSS. Visual acuity loss is usually mild and only occurs in 40–50% of patients.

Classification systems for malformations of the cerebellum are varied and are constantly being revised as greater understanding of the underlying genetics and embryology of the disorders is uncovered. A classification proposed by Patel S in 2002 divides cerebellar malformations in two broad groups; those with cerebellar hypoplasia and; those with cerebellar dysplasia.

- I. Cerebellar hypoplasia

- A. Focal hypoplasia

- 1. Isolated vermis

- 2. One hemisphere hypoplasia

- B. Generalized hypoplasia

- 1. With enlarged fourth ventricle (“cyst,”), Dandy-Walker continuum

- 2. Normal fourth ventricle (no “cyst”)

- a. With normal pons

- b. With small pons i. Normal foliation

- a) Pontocerebellar hypoplasias of Barth, types I and II

- b) Cerebellar hypoplasias, not otherwise specified

Neuroimaging like MRI is important. However, there was considerable intrafamilial variability regarding neuroimaging, with some individuals showing normal MRI findings. Early individual prognosis of such autosomal recessive cerebellar ataxias is not possible from early developmental milestones, neurological signs, or neuroimaging.

The syndrome causes cerebellar ataxia (balance and coordination problems), mental retardation, congenital cataracts in early childhood, muscle weakness, inability to chew food, thin brittle fingernails, and sparse hair.

Small stature, mild to severe mental retardation and dysarthria (slow, imprecise speech) are usually present.

Various skeletal abnormalities (e.g., curvature of the spine) and hypergonadotropic hypogonadism often occur.

Muscle weakness is progressive, but life expectancy is near normal.

Symptoms typically begin sometime between the ages of 5 to 15 years, but in Late Onset FA may occur in the 20s or 30s. Symptoms include any combination, but not necessarily all, of the following:

- Muscle weakness in the arms and legs

- Loss of coordination

- Vision impairment

- Hearing impairment

- Slurred speech

- Curvature of the spine (scoliosis)

- High plantar arches (pes cavus deformity of the foot)

- Diabetes (about 20% of people with Friedreich's ataxia develop carbohydrate intolerance and 10% develop diabetes mellitus)

- Heart disorders (e.g., atrial fibrillation, and resultant tachycardia (fast heart rate) and hypertrophic cardiomyopathy)

It presents before 22 years of age with progressive staggering or stumbling gait and frequent falling. Lower extremities are more severely involved. The symptoms are slow and progressive. Long-term observation shows that many patients reach a plateau in symptoms in the patient's early adulthood. On average, after 10–15 years with the disease, patients are usually wheelchair bound and require assistance with all activities of daily living.

The following physical signs may be detected on physical examination:

- Cerebellar: nystagmus, fast saccadic eye movements, truncal ataxia, dysarthria, dysmetria.

- Lower motor neuron lesion: absent deep tendon reflexes.

- Pyramidal: extensor plantar responses, and distal weakness are commonly found.

- Dorsal column: Loss of vibratory and proprioceptive sensation occurs.

- Cardiac involvement occurs in 91% of patients, including cardiomegaly (up to dilated cardiomyopathy), symmetrical hypertrophy, heart murmurs, and conduction defects. Median age of death is 35 years, while females have better prognosis with a 20-year survival of 100% as compared to 63% in men.

20% of cases are found in association with diabetes mellitus.

Non-progressive early onset ataxia and poor motor learning are the commonest presentation.

Onset of symptoms usually occur in early adulthood and is characterized by intention tremor, progressive ataxia, convulsions, and myoclonic epileptic jerks.

Tremors usually affect one extremity, primarily the upper limb, and eventually involve the entire voluntary motor system. Overall, the lower extremity is usually disturbed less often than the upper extremity.

Additional features of the syndrome include: an unsteady gait, seizures, muscular hypotonia, reduced muscular coordination, asthenia, adiadochokinesia and errors with estimating range, direction, and force of voluntary movements. Mental deterioration can occur, however it is rare.

SCA6 is typified by progressive and permanent cerebellar dysfunction. These cerebellar signs include ataxia and dysarthria, likely caused by cerebellar atrophy. Prior to diagnosis and the onset of major symptoms, patients often report a feeling of "wooziness" and momentary imbalance when turning corners or making rapid movements. The age at which symptoms first occur varies widely, from age 19 to 71, but is typically between 43 and 52. Other major signs of SCA6 are the loss of vibratory and proprioceptive sensation and nystagmus.

While most patients present with these severe progressive symptoms, others, sometimes within the same family, display episodic non-progressive symptoms more similar to episodic ataxia. Still others present with symptoms common to both SCA6 and familial hemiplegic migraine.

Most of the signs and symptoms of the Joubert syndrome appear very early in infancy with most children showing delays in gross motor milestones. Although other signs and symptoms vary widely from individual to individual, they generally fall under the hallmark of cerebellum involvement or in this case, lack thereof. Consequently, the most common features include ataxia (lack of muscle control), hyperpnea (abnormal breathing patterns), sleep apnea, abnormal eye and tongue movements, and hypotonia in early childhood. Other malformations such as polydactyly (extra fingers and toes), cleft lip or palate, tongue abnormalities, and seizures may also occur. Developmental delays, including cognitive, are always present to some degree.

Those suffering from this syndrome often exhibit specific facial features such as a broad forehead, arched eyebrows, ptosis (droopy eyelids), hypertelorism (widely spaced eyes), low-set ears and a triangle shaped mouth. Additionally, this disease can include a broad range of other abnormalities to other organ systems such as retinal dystrophy, kidney diseases, liver diseases, skeletal deformities and endocrine (hormonal) problems.

Autosomal dominant cerebellar ataxia (ADCA) is a form of spinocerebellar ataxia inherited in an autosomal dominant manner. ADCA is a genetically inherited condition that causes deterioration of the nervous system leading to disorder and a decrease or loss of function to regions of the body.

Degeneration occurs at the cellular level and in certain subtypes results in cellular death. Cellular death or dysfunction causes a break or faulty signal in the line of communication from the central nervous system to target muscles in the body. When there is impaired communication or a lack of communication entirely, the muscles in the body do not function correctly. Muscle control complications can be observed in multiple balance, speech, and motor or movement impairment symptoms. ADCA is divided into three types and further subdivided into subtypes known as SCAs (spinocerebellar ataxias).

Most patients begin to use a wheelchair for movement around age 30-40. Death usually occurs in their 60s, but some have been reported to live longer.

Harding ataxia, also known as Early onset cerebellar ataxia with retained reflexes (EOCARR), is an autosomal recessive cerebellar ataxia originally described by Harding in 1981. This form of cerebellar ataxia is similar to Friedreich ataxia including that it results in poor reflexes and balance, but differs in several ways, including the absence of diabetes mellitus, optic atrophy, cardiomyopathy, skeletal abnormalities, and the fact that tendon reflexes in the arms and knees remain intact. This form of ataxia is characterized by onset in the first 20 years, and is less severe than Friedreich ataxia. Additional cases were diagnosed in 1989, 1990, 1991, and 1998.