MEN (General Swiss-German Mennonite)

Inheritance: autosomal recessive
Genes: FLVCR1

Posterior column ataxia with retinitis pigmentosa
AXPC1
PCARP

Ataxia
Sensory neuropathy
Inanition
Scoliosis muscle weakness
Pigmentary retinopathy
Retinitis pigmentosa
Night blindness
Maculopathy
Areflexia

Retinitis Pigmentosa With Ataxia

Clinical Characteristics

General description (for patients): 

Children have reduced vision early in life and often are severely handicapped by the third decade of life.  Night blindness begins in the first decade of life and children develop tunnel vision somewhat later.  An ophthalmologist can see changes in the retina by 6 months of age when patchy areas of changes in pigmentation are present.
Walking is delayed and is unsteady as children grow.  Later they are unable to walk by themselves.  There is general weakness of muscles and this may lead to abnormal curvature of the spine.  Mental functioning remains normal.

Medical description:

This is a form of posterior column ataxia associated with a pigmentary retinopathy sometimes called retinitis pigmentosa.  Visual difficulties are noted by one year of age although retinal pigment changes may be seen by 6 months.  Nightblindness and constricted visual fields are evident during the first decade and visual acuity worsens causing severe handicapping by the third decade.
Locomotion is delayed and never normal.  Motor conduction velocities are subnormal.  Proprioceptive deficits and areflexia appear in early childhood and slowly progress.  Sensory neuropathy with loss of vibratory and position sense, astereognosia and agraphesthesia are seen in the first decade.  All symptoms gradually worsen and unassisted walking becomes impossible.  Loss of large myelinated fibers are seen on sural nerve biopsies and hyperintense signals in the posterior spinal columns can be seen on MRI but no anatomic changes have been described in the cerebrum or cerebellum.

Genetics:

This is an autosomal recessive disorder resulting from homozygous mutations in FLVCR1 (1q32.2-q41). This disorder has some clinical similarities to Biemond 1 syndrome but differs in the inheritance pattern and the molecular basis.
This disorder has been described in 5 individuals of a large kinship in Pennsylvania.  The original ancestor immigrated to America in 1765 from an area near the German-Swiss border.

Treatment:

Treatment is largely supportive.

Prognosis:

The neurological symptoms gradually worsen and patients become wheelchair bound in adult life.  Nothing is known regarding longevity.

Ancillary treatments and support:

Physical therapy may be beneficial early in the disease and low vision aids may improve the quality of life in young patients.

Specialists and specialty centers:

Neurologists, pediatricians, orthopedists

References:

Higgins JJ, Morton DH, Patronas N, Nee LE. An autosomal recessive disorder with posterior column ataxia and retinitis pigmentosa. Neurology. 1997 Dec;49(6):1717-20. PubMed PMID: 9409377.
 
Rajadhyaksha AM, Elemento O, Puffenberger EG, Schierberl KC, Xiang JZ, Putorti ML, Berciano J, Poulin C, Brais B, Michaelides M, Weleber RG, Higgins JJ. Mutations in FLVCR1 cause posterior column ataxia and retinitis pigmentosa. Am J Hum Genet. 2010 Nov 12;87(5):643-54. PubMed PMID: 21070897.