Thanatophoric Dwarfism

A severe form of micromelic dwarfism with narrow thorax with short ribs, severe hydrocephalus, and hydronephrosis. Death generally occurs in the first hours of life.

Thanatophoric Dysplasia.

1:10,000 to 1:35,000 live births.

Autosomal dominant inheritance but most cases are de novo mutations.

Caused by mutation in the fibroblast growth factor receptor-3 gene (FGFR3, which belongs to the tyrosine kinase receptors) located on 4p13.6. Formation of cysteine residues with disulfide bonds between the extracellular domains of mutant monomers has been reported as resulting from FGFR3 mutation. Perturbation of terminal chondrocyte differentiation could be the final result of this mutation.

Clinically evocated in a baby with severe shortening of the limbs, narrow thorax, macrocephaly, and normal trunk length. Antenatal diagnosis on ultrasonographic findings is possible.

Major skeletal deformations observed involve: skull (macrocephaly, frontal bossing, depressed nasal bridge), limbs (micromelic dwarfism, brachydactyly, enlarged and bowed diaphysis), and trunk (abnormal rib with narrow rib cage, scapula anomaly, intervertebral disk anomaly, abnormal vertebral size, and pelvis anomaly). Other clinical features can include glaucoma, temporal lobe heterotopias, hydrocephalus, profound mental retardation, and hypotonia in survivors. Respiratory insufficiency is frequent because of restrictive thoracic deformations.

Because of the early death, it will be extremely rare for an anesthesiologist to provide care for surgery, except for airway and cardiovascular support at birth. If the patient survives, a complete evaluation of neurological function (clinical, EEG, CT) must be obtained. Evaluate respiratory function (clinical, chest radiographs, pulmonary function test, arterial blood gas analysis).

Careful intraoperative positioning is needed. Both arterial and venous access can be difficult because of limb deformations. Regional anesthesia is not contraindicated but can be difficult to perform. Postoperative physiotherapy is useful. Postoperative mechanical ventilatory support may be necessary.

Avoid atropine and other cholinergic drugs because of glaucoma.

Thanatophoric Dysplasia with Kleeblattschädel (Cloverleaf Skull with Thanatophoric Dwarfism; Thanatophoric Dysplasia type II): Autosomal dominant, lethal micromelic dwarfism with cloverleaf head and small facies; also caused by mutations in FGFR3.

Thanatophoric Dysplasia, Glasgow Variant (Neonatally Lethal Short-Limb Skeletal Dysplasia, Glasgow type): Autosomal recessive disorder that combines dwarfism with cataracts, anemia, and hepatosplenomegaly.

Jarcho-Levin Syndrome: A rare genetic disorder characterized by distinctive malformations including short thorax because of fusion of thoracic vertebrae and ribs. This skeletal problems often leads to respiratory insufficiency, pneumonia resulting in life-threatening complications. Other features include vertebral dysplasia, and hemivertebrae. In addition, abnormalities with the cervical vertebrae may cause shortness of the neck, limited neck motion, and an abnormally low hairline appearance. During the infancy period, the abdomen may be abnormally prominent and the arms and legs may appear unusually long suggesting often a marfanoid appearance. This disorder is thought to be inherited as an autosomal recessive genetic trait.

Diastrophic Dysplasia: An autosomal recessive inherited form of short-limb dwarfism associated with spine ...