Hypomyelination neuropathy-arthrogryposis syndrome

What it is

Hypomyelination neuropathy-arthrogryposis syndrome is a rare, genetic, limb malformation syndrome characterized by multiple congenital distal joint contractures (incl. talipes equinovarus and both proximal and distal interphalangeal joint contractures of the hands) and very severe motor paralysis at birth (i.e. lack of swallowing, autonomous respiratory function and deep tendon reflexes), leading to death within first 3 months of life. Fetal hypo- or akinesia, late-onset polyhydramnios and dramatically reduced, or absent, motor nerve conduction velocities (<10 m/s) are frequently associated. Nerve ultrastructural morphology shows severe abnormalities of the nodes of Ranvier and myelinated axons.

Key facts

Prevalence

<1 / 1 000 000

Age of onset

Antenatal

Inheritance

Autosomal recessive

Classified as

Malformation syndrome

Prevalence figures describe populations, not individuals, and are often estimates from a single study. Where the figure is an incidence or a birth prevalence, it says so.

Signs and symptoms

These ranges are how often a sign appears across everyone diagnosed, not a prediction for one person — most people have some of these and not others. Orphanet also records findings that are specifically absent in this disease; those are in the data but not listed here.

Genes

ICD-10 codes

ICD-10 has no distinct code for most rare diseases, so many are filed under the nearest available one. A shared code identifies the group, not this disease — the ORPHAcode above is what identifies it.

Cross-references