Which patient groups have the highest prevalence of olivopontocerebellar atrophy (OPCA)?

Updated: Dec 17, 2018
  • Author: Sombat Muengtaweepongsa, MD, MSc; Chief Editor: Selim R Benbadis, MD  more...
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No apparent racial preference is observed in OPCA. This is unlike Machado-Joseph disease, which has a predominance in certain Azorean, Indian, and Italian families.

A male preponderance is observed in familial cases of OPCA, with a male-to-female ratio of 2:1. However, no such distinction is seen in sporadic cases.

The mean age of onset of sporadic OPCA is 53 years. The mean age of onset of familial OPCA is 28 years (excluding the infantile forms in Table 2 in Causes).

Table 2. Extremely Rare Types of OPCAs (Open Table in a new window)


OPCA Names

Other Names

Genetic Pattern



Pontocerebellar hypoplasia type 1, PCH-1

Pontocerebellar hypoplasia with infantile spinal muscular atrophy, pontocerebellar hypoplasia with anterior horn cell disease

Autosomal recessive

Cerebellar hypoplasia plus motor neuron loss; sometimes called a combination of olivopontocerebellar degeneration plus spinal muscular atrophy; present from birth; patients usually die in infancy [27, 28]


Pontocerebellar hypoplasia type 2, PCH-2

Pontocerebellar hypoplasia with progressive cerebral atrophy, Volendam neurodegenerative disease

Autosomal recessive

Congenital microcephaly, extrapyramidal findings, epilepsy; autopsy in one case showed that the olivopontocerebellar system was the most heavily involved in degeneration


Pontocerebellar hypoplasia type, PCH-3, Pontocerebellar hypoplasia with optic atrophy

Cerebellar atrophy with progressive microcephaly, CLAM

Autosomal recessive; gene map locus 7q11-q21Gene map locus 7q11-q21

Onset in infancy or childhood, cerebellar atrophy with progressive microcephaly; on MRI of small brainstem, small cerebellar vermis and atrophy of the cerebellum and cerebrum; ataxia, truncal hypotonia, and exaggerated deep tendon reflexes; one patient had optic atrophy; seizures common [29]


Pontocerebellar hypoplasia type 4, PCH-4

Fatal infantile encephalopathy with olivopontocerebellar hypoplasia

Probably autosomal recessive, possibly autosomal dominant or maternal transmission; biochemical defect and gene locus not known

Patients die in infancy; severe olivopontocerebellar hypoplasia on autopsy [30, 31]


Pontocerebellar hypoplasia type 5, PCH-5

Olivopontocerebellar hypoplasia, fetal onset

Genetics not clear

Pontocerebellar hypoplasia is a heterogeneous group of disorders characterized by an abnormally small cerebellum and brainstem with significant hypoplasia of the olivae, the pons, and the cerebellum; patients typically die in infancy [31]


De Sanctis-Cacchione syndrome


Gene map locus 10q11; an excision repair gene named variously ERCC6, CKN2, COFS, and CSB causing Cockayne syndrome type B (CSB; 133540) or genes of xeroderma pigmentosum, usually XPA (ie, complementation group A); 278700 9q22.3 or more rarely, other genes associated with xeroderma pigmentosum; autosomal recessive

Xeroderma pigmentosum (severe sun sensitivity), mental retardation, dwarfism, and progressive neurological deterioration; overlaps with known types of xeroderma pigmentosum and Cockayne syndrome, especially XPA and CSB, apparently as allelic variants but other unknown factors may bring out the olivopontocerebellar (and cerebral) atrophy [32, 33, 34]


Congenital disorder of glycosylation, type Ia


Phosphomannomutase-2 (PMM2; 601785); autosomal recessive

Severe congenital psychomotor retardation, generalized hypotonia, hyporeflexia, and trunk ataxia, neonatal-onset OPCA, peripheral neuropathy, retinitis pigmentosa; defects in other systems include heart and musculoskeletal systems; severe neonatal neurodegenerative disease; some patients have olivopontocerebellar phenotype; usually death in infancy or childhood [35, 36]

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