Hypoglossia-Hypodactyly Syndrome

A rare disease characterized by the association of aglossia (absence of tongue), adactylia (absence of fingers or toes) and limb, craniofacial and other, less frequent malformations.

Clinical description

It was first described in 1932, but in 1950 Hanhart described three cases of aglossia with associated limb defects and gave his name to the syndrome. Several similar cases have since been reported allowing a better definition of the associated malformations. Craniofacial anomalies include microstomia (small mouth), micrognathia, hypoglossia, variable clefting or aberrant attachments of tongue, mandibular hypodontia, cleft palate, cranial nerve palsies (including Möebius sequence), broad nose, telecanthus, lower eyelid defects, and facial asymmetry. The limb defects are represented by hypoplasia, varying from absence of the distal phalanx to total adactyly or partial limb amputation, with or without syndactyly. Limb defects usually involve all four limbs. Among the less constant malformations are gastroschisis and splenogonadal fusion. Intelligence and stature are generally normal, but patients with intellectual deficit have been reported. Early feeding and speech difficulties may occur.

Etiology

About 30 cases of Hanhart syndrome were reported in the literature between 1932 and 1991, and a few cases of intra-familial recurrence led to a hypothesis of mutation of an autosomal recessive gene being responsible for this condition. This genetic hypothesis, disproved in 1973, has now been replaced by a more plausible hypothesis: the abnormalities are probably the disruptive consequence of hemorrhagic lesions occurring during development. Vascular problems presumed to result from these lesions would be more likely to occur in distal regions, such as the distal limbs, tongue, and occasionally parts of the brain. The features described in patients diagnosed with aglossia adactylia after CVS are generally of lower severity than those described in patients with the Hanhart syndrome, but these two conditions probably belong to the same spectrum of anomalies. Chorionic villous sampling (CVS), when performed before week 10 of amenorrhoea, has been associated with this disorder, giving further credence to a disruptive vascular hypothesis. Since the association between early CVS and oromandibular limb dysgenesis has been confirmed, CVS is now performed later in pregnancy, and cases of this disruptive malformation are currently rarely reported in the literature.

Differential diagnosis

Some of the listed symptoms may be confounded with those of Nager syndrome or acro-facial dysostosis. Both Nager syndrome and acro-facial dysostosis differ from aglossia adactylia in the kind of facial dysmorphia (in Nager syndrome the ears are malformed and malar hypoplasia is associated with downslanting palpebral fissures) and in the type of limb anomalies (preaxial defects are more common in Nager syndrome whereas transverse defects are more common in aglossia-adactyly).

Management and treatment

Treatment may involve orthopedic and/or plastic surgery for the limb anomalies.