anomalous teeth

Nystagmus-Split Hand Syndrome

Clinical Characteristics
Ocular Features: 

The only consistent ocular finding is pendular nystagmus beginning at birth.  There is some evidence that the eye movements decrease with age.  Acuity in a 46 year old female was recorded to be 20/40 in each eye whereas one of her children had 20/70.  Two patients (father and daughter) have been described as having cataracts and “fundus changes”, not further defined.  Other patients have been described with normal fundi.  The ERG has been normal in several patients.  Some authors have noted hypertelorism.

The ocular phenotype requires further definition.  For example, in a single published photograph of a young child the medial portion of the eye brows is sparsely populated and all eyelashes in the medial one-third of the upper lid appear to be absent.  This has not been commented on in publications, however.

Systemic Features: 

The hand and foot malformation is severe, described as split-hand/split foot deformity.  It may involve all four extremities or just the upper extremity with monodactyly.  When the hand is involved, it may be called a lobster-claw deformity, or ectrodactyly.  The middle digit is characteristicly missing but other fingers and toes are sometimes absent.

The teeth erupt late, some may be missing and others are often poorly formed. Frontal bossing, sunken cheeks, and thick and everted lips may be part of the facial phenotype.


The genetics of Karsch-Neugebauer is obscure although the majority of evidence is consistent with autosomal dominant inheritance.  Parent-child transmission and male-to-male transmission have been observed.  In other families the parents are normal but reduced penetrance has not been ruled out.  Further, there are several types of split-hand deformities but this is the only one associated with nystagmus.  No locus or mutation has been found for this condition.

Autosomal dominant
Treatment Options: 

Surgical reconstruction can sometimes improve hand function.

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