A to Z of syndromes

A-Z syndromes: Yunis-Varon syndrome

An insight into this rare genetic disorder in which both parents are recessive gene carriers

An insight into this rare genetic disorder in which both parents are recessive gene carriers

Webbed_fingers
Syndactyly is associated with Yunis-Varon syndrome and surgery is an option to separate the digits
Picture: SPL

Yunis-Varon syndrome is a rare genetic disorder, inherited as an autosomal recessive trait. This means that both parents have to be carriers of a recessive gene and the risk to the parents of having an affected child is 1:4 with each pregnancy.

Consanguinity between the parents increases the risk. The syndrome was first identified in 1980, by geneticists Yunis and Varon. It affects males and females, and has been identified in several races.

Children with the syndrome may be born without collarbones, can have cardiac anomalies, microcephaly, ear abnormalities, anteverted nares, midfacial hypoplasia, tented upper lip and micrognathia.

The hair of the eyebrows and eyelashes can be sparse or absent. The dental profile can include supernumerary teeth, deficient cementum, retained teeth, displaced teeth or an absence of secondary eruption.

Infants with Yunis-Varon syndrome can also be born small, be difficult to feed and exhibit faltering growth as they mature.

Syndactyly has also been associated with Yunis-Varon syndrome and the distal phalanges of the fingers or toes may be absent or underdeveloped leading to short fingers and toes, and absent fingernails. Thumbs and the big toe can also be missing.

There is a trajectory of severity and, although there have been reports of severe developmental delays and learning disability, there is also the possibility of normal intellect.

Treatment and management

There is no cure for the condition, treatment and management depends on the way each individual is affected. There are insufficient numbers of cases worldwide to provide accurate information about life expectancy. Some information suggests the condition is often lethal resulting in miscarriage, stillbirth and neonatal death.

The syndrome could be identified with antenatal screening if the infant was affected by a skeletal or cardiac anomaly, which could be seen on a scan. Identified and affected families can receive genetic counselling and support.

Missing clavicles are unlikely to affect an individual significantly, as long as the thoracic cage is otherwise stable. Cardiac surgery can be performed. Orthopaedic surgery and ongoing management would be possible for children with skeletal anomalies.

Surgery for syndactyly is an option to separate the digits. This can be performed for functional reasons or for cosmetic result. These operations are usually staged, may involve skin grafts and subsequent surgical revisions may be required if the graft or scar tissue does not grow along with the child’s hand.

Case study

A dysmorphic three-day-old girl was brought to the genetics clinic for a follow-up hospital appointment by her grandparents. The mother had not encountered any problems with the pregnancy and had given birth normally, as a planned home delivery.

The infant had been well at delivery. The appointment had been made by the GP who examined her shortly after birth.

A careful examination identified that the infant was microcephalic, with wide fontanelles. Her eyes were prominent and her mouth an unusual shape. Her big toes were absent, her fingers and thumbs were short. When handled the child was noted to be hypotonic, when turned over the skin on the back of the neck appeared loose.

X-rays confirmed the medical teams’ concerns that this was a child affected by Yunis-Varon syndrome because of the absence of finger bones and hypoplastic clavicles. Fortunately, the echocardiogram was normal, but the computed tomography scan confirmed microcephaly and suggested undeveloped gyri on the brain surface, which could affect cognitive functioning. The family wanted to have genetic counselling.

 

Further information


About the author

Doreen Crawford is a nurse adviser with consultancy Crawford McKenzie and consultant editor of Nursing Children and Young People

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