The Moebius sequence consists of a number of facial anomalies attributed to
paralysis of the 6th and 7th cranial nerves bilaterally.
- Usually sporadic (1), but
rare familial cases have been reported (2).
- Pathology.
- Hypoplasia to absence
of the central brain nuclei.
- Destructive
degeneration of the central brain nuclei (most common type).
- Peripheral nerve
involvement.
- Myopathy.
The variable features are usually due to insufficient blood supply to
structures supplied by the developing subclavian artery (3,4).
- Craniofacial.
- Micrognathia (due to
impairment of jaw mobility).
- Ptosis.
- Some patients have
more extensive cranial nerve involvement (3rd, 4th, 5th, 9th, 10th and
12th). The tongue may be small or have limited mobility if the 12th nerve
is involved.
- Limbs.
- Reduction defects
usually in the upper extremities and range from transverse deficiencies
to absent digits.
- Talipes equinovarus
(one third of cases).
- Syndactyly.
- Poland's sequence.
- Klippel-Feil anomaly
occasionally.
Some workers believe that the Moebius sequence, Poland and Klippel-Feil
syndromes, all of which occur in various combinations in an individual, should
be grouped together under a single category, the subclavian artery disruption
sequence (3). All these conditions result from a decreased blood flow in the
subclavian artery, vertebral artery and or their branches during or around the
6th week of development.
- Baraitser M. Genetics of
Mobius syndrome. J Med Genet 1977;14:415.
- Sugarman GI, Stark HH. Mobius
syndrome with Poland's anomaly. J Med Genet 1973;10:192-196.
- Bouwes-Bavinck JN, Weaver DD.
Subclavian artery supply disruption sequence: Hypothesis of a vascular
etiology for Polands, Klippel-Feil and Moebius anomalies. Am J Med Genet
1986;23:903.
- St Charles S et.al. Mobius
sequence: Further in vivo support for the subclavian artery disruption sequence.
Am J Med Genet 1993;47:289.