Acrofacial dysostosis Nager type

Overview

Nager acrofacial dysostosis is a genetic disorder that affects the limbs and face. The signs and symptoms of Nager acrofacial dysostosis vary among affected individuals, even among those in the same family.

Symptoms

  • Conductive deafness
  • Speech articulation difficulty
  • Underdeveloped cheekbone
  • Down-slanting opening between eyelids
  • High nose bridge
  • Hypoplasia of the zygomatic bone
  • Neurological speech impairment
  • Skeletal dysplasia
  • Hearing impairment

Limb anomalies more commonly reported in people with Nager acrofacial dysostosis, include:

  • Underdeveloped or absent radius
  • Underdeveloped or absent thumbs
  • Thumbs with two knuckles (triphalangeal thumbs)
  • Joined radius and ulnar bones (radioulnar synostosis)

Facial anomalies more commonly reported in people with Nager acrofacial dysostosis, include:

  • Underdeveloped jaw (micrognathia)
  • Underdeveloped cheekbones
  • Downward slanting eyes
  • Reduced number of eyelashes
  • Small missing segment of the lower eyelid (eyelid coloboma)
  • Lack of development of the internal and/or external ear
  • Cleft palate

Causes

There is evidence that at least some cases of Nager acrofacial dysostosis are caused by heterozygous mutation in the SF3B4 gene which is located on chromosome 1q12-q21.

Most cases of Nager acrofacial dysostosis have been sporadic. Sporadic means that the condition occurs for the first time in a family due to a new mutation. People with sporadic disease tend to be the first person affected in his or her family, however they are still at risk for passing the condition on to their future children.

There have been reports of families with Nager acrofacial dysostosis demonstrating an autosomal dominant and others autosomal recessive pattern of inheritance.

Autosomal dominant means each child of an affected parent has a 50-50 chance of inheriting the mutant gene. If a child does not inherit the mutant gene, he or she will not develop the disease and cannot pass it to subsequent generations.

Autosomal recessive means the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition. These parents have a 25% chance with each pregnancy of having a child with Nager acrofacial dysostosis.

Prevention

Early prenatal recognition of the syndrome is important to provide parents with the option of pregnancy termination, and in case of pregnancy continuation, appropriate management by an experienced team of neonatologists is mandatory to ensure neonatal survival.

Diagnosis

The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Prognosis

Neonates with Nager syndrome may present with acute upper airway obstruction due to severe micrognathia.

Treatment

In infants with Nager acrofacial dysostosis who experience respiratory distress require immediate attention and may require a tracheostomy. A tracheostomy is a surgical procedure on the neck that opens a direct airway through an incision in the windpipe.

Infants with feeding difficulties may require surgery and/or placement of a feeding tube (gastrostomy). Surgery can be performed to repair cleft palate and often micrognathia. Cosmetic surgery, especially for eyelids, can be performed to ensure complete closure of eyelids at night in order to prevent injury of the cornea. Surgical treatment is best accomplished at a craniofacial center with expertise in plastic surgery, otolaryngology, orthodontics, and dentistry. Hearing aids for individuals with conductive hearing loss should be offered.