Nance-Horan Syndrome

At a glance

Very rare congenital inherited disorder that combines congenital bilateral cataracts, dental anomalies, facial dysmorphism, and intellectual deficit.

Synonyms

Mesiodens-Cataract Syndrome; Cataract-Dental Syndrome; X-Linked Cataract-Hutchinsonian Teeth Syndrome.

Incidence

Several kindreds have been described since this condition was defined in 1974. It is fully expressed in Wales only.

Genetic inheritance

Transmitted as an X-linked trait.

Pathophysiology

Mutations of the NHS gene on the short arm of chromosome X (Xp22.2-p22.1). This gene encodes a functional WAVE homology domain (WHD) and controls cell morphology by maintaining the integrity of the circumferential actin ring and controlling lamellipod formation. The differential expression of two isoforms, NHS-A and NHS-1A, differently localized in the cell, may in part explain the variable clinical manifestations.

Diagnosis

Bilateral congenital cataracts with impaired vision, extra incisors, anteverted pinnae, short fourth metacarpals, and variable anomalies. Mental deficiency is present in some patients. Dental anomalies are worse in related males than in females.

Clinical aspects

Males have dense nuclear cataracts and microcorneas, whereas heterozygous females have posterior Y-sutural cataracts, small corneas, and only slightly reduced vision. Teeth show nonsyphilitic hutchinsonian incisors, supernumerary teeth, irregular diastema, and cone-shaped incisors. Dolichocephaly and mandibular prognathism occur, with a high-nasal bridge, prominent, anteverted pinnae, and short metacarpals. Developmental delay may be seen. Patients have a marfanoid habitus, and males are often blind.

Precautions before anesthesia

No literature about this condition and anesthesia. Patients may be blind or mentally handicapped.

Anesthetic considerations

Oral and dental anomalies may cause technical difficulties during direct laryngoscopy and tracheal intubation. Blind and/or mentally handicapped children need much reassurance. The presence of a parent and/or premedication may help when airway difficulties are not expected. Particular attention to fragile teeth.

Pharmacological implications

No specific interactions.

Other condition to be considered

• ☞Robinow Syndrome: Characterized by “fetal facies,” crowded teeth, gingival enlargement, and ankyloglossia. They are combined with mesomelic shortening of the forearm and hypoplastic genitalia. No cataracts.

References