Nager syndrome is a congenital (present at birth) condition affecting the bones and tissues of the face. It also affects the arms and hands, and occasionally the legs and feet.
Early in pregnancy, the cheekbones, eye sockets and jaws do not develop properly. This causes a characteristic appearance with downward sloping eyes and a small lower jaw. Nager syndrome is similar to Treacher-Collins syndrome, with additional differences of the arms and hands. It is often associated with cleft palate.
As children with Nager syndrome have a characteristic appearance, no specific diagnostic tests are needed. Imaging scans, such as x-ray, CT or MRI, may be suggested depending on the features and needs of the child. Imaging may also be needed to examine the internal structures of the ear alongside hearing tests to diagnose hearing loss.
Nager syndrome may be a genetic condition caused by a mutation (change) on a specific gene. However, the specific gene(s) causing Nager syndrome have not yet been identified. The gene(s) suspected in Nager syndrome alter the development of the first and second pharyngeal arches early in pregnancy. The pharyngeal arches are structures located on either side of the head and neck that develop into the features of the face and neck. In particular, the first and second pharyngeal arches form into the nerves and muscles needed for showing facial expressions and chewing, the outer ear and the structures within the middle ear.
In Nager syndrome, there are typically associated differences with arm and hand development.
Children with Nager syndrome have a characteristic appearance due to the differences in the development of their cheekbones, jaws and eye sockets. If the lower jaw is very small or underdeveloped, breathing difficulties may become apparent at or shortly after birth. A small jaw can also cause feeding difficulties.
The ears are often affected in children with Nager syndrome, either being absent (anotia) or small (microtia). If the internal structures of the ear are also underdeveloped this can lead to hearing impairment.
The arms and hands are also affected in Nager syndrome. Often, the elbow joint is stiff so bending the arm is difficult. The radius bone in the forearm may be missing or underdeveloped causing the hand to be bent inwards towards the body (radially deviated). This can affect all the structures on the radial side of the upper limb, including the bones and soft tissues (muscles, tendons, joints, nerves and blood vessels). The most common hand difference in children with Nager syndrome is an underdeveloped or absent thumb on both hands. The other fingers may be abnormally curved (clinodactyly), stiff or webbed (syndactyly). In some children, their legs and feet are similarly affected.
Rarely, other structures in the body are also affected.
The outlook for children born with Nager syndrome is variable depending on the severity of their symptoms and the impact it has on functions such as breathing and hearing. They will require long term monitoring, particularly during periods of growth in childhood and adolescence. Surgeries are more frequent in early childhood but are typically completed by the time the child is in their mid-twenties. Some children and families benefit from psychological input at various stages throughout childhood and adolescence.
As Nager syndrome can affect various areas of the head and face, treatment is best delivered at a specialist centre where a multidisciplinary team approach can be taken. The multidisciplinary team will usually include craniofacial (skull and face) surgeons, maxillofacial (dental and jaw) surgeons, ear, nose and throat (ENT) surgeons, hand surgeons, plastic surgeons, audiologists (hearing specialists), dentists and orthodontists, geneticists, pediatricians, and speech and language therapists, with other specialists brought in as needed.
Supporting a child’s breathing is the first priority. For some children, their anatomy is so different that they need a tracheostomy (an artificial opening into the windpipe) to allow them to breathe. Other children may only need breathing support at night. Feeding problems may be helped with a special bottle, a feeding tube or a gastrostomy tube which goes directly into the stomach, bypassing the mouth and throat.
If the thumb is present but weak, surgery can be undertaken to stabilize any unstable joints and strengthen the thumb by taking a tendon or a muscle from elsewhere in the hand. If the thumb is absent or unstable, the index finger on that hand may be moved to the thumb position (pollicization). Finger webbing (syndactyly), if causing a problem with function, may be corrected in a series of operations during childhood.
Later in childhood, the underdeveloped jaw may require treatment, often with bone grafts and jaw distraction. This is a long-term treatment but has good results for the majority of children.
Ear reconstruction can also be carried out in later childhood, either creating a bigger ear from the child’s rib cartilage or from a plastic (Medpor) implant.
Ear reconstruction improves the appearance of the ear but it will not improve function. Children with hearing impairment will benefit from support in terms of hearing aids or cochlear implant as well as speech and language therapy.
As the bones continue to grow during childhood and adolescence, further surgery may be needed to improve facial appearance.
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