endochrondrial ossification

Asphyxiating Thoracic Dysplasia 1

Clinical Characteristics
Ocular Features: 

This is a genetically and clinically heterogeneous condition for which the nosology remains to be worked out.  Not all patients have ocular disease but those who survive infancy may have a pigmentary retinopathy resembling retinitis pigmentosa.  In fact, a 5 year old presented with symptoms of visual loss and night blindness only.  The severeity of the systemic malformations has so far precluded a full description of the ocular phenotype.

Systemic Features: 

The most life-threatening and characteristic systemic feature of ATD is short-ribbed thoracic constriction with respiratory insufficiency.  The chest is small and narrow and sometimes described as bell-shaped.  This deformity can lead to death by asphyxiation, and is a serious risk during infancy.  Other individuals live to adulthood and may have only minimal respiratory difficulties.  Patients who survive childhood can develop cystic renal and hepatic disease.  Pancreatic fibrosis has also been reported.  Brachydactyly and postaxial polydactyly are sometimes present and involve the feet more commonly than the hands.  Short stature secondary to short limbs is frequently noted.

Genetics

Jeune syndrome, or at least some forms of it, is an autosomal recessive condition.  Consanguinity is often present.  A locus (15q13) containing homozygous mutations in ATD has been proposed as one candidate site.  There is considerable genetic heterogeneity with at least 5 types described, all with mutations in different genes.

Another disorder with some similar features causing respiratory distress is Majewski syndrome (263520).

Pedigree: 
Autosomal recessive
Treatment
Treatment Options: 

Assisted ventilation can be lifesaving in milder cases.  Thoracic reconstruction has also been helpful in a few individuals.  However, careful patient selection is necessary since some patients have severe pulmonary hypoplasia with underdeveloped alveoli. Ursodeoxycholic acid may slow the progression of the liver disease.

References
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