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Achondrogenesis Type 1B.

Source

GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019.
2002 Aug 30 [updated 2013 Nov 14].

Author information

1
Associate Professor; Head, Division of Molecular Pediatrics, Lausanne University Hospital, Lausanne, Switzerland
2
Laboratory of Molecular Pediatrics, Lausanne University Hospital, Lausanne, Switzerland
3
Senior Lecturer, Division of Molecular Pediatrics, Lausanne University Hospital, Lausanne, Switzerland
4
Professor of Pediatrics, Department of Pediatrics, Lausanne University Hospital, Lausanne, Switzerland

Excerpt

CLINICAL CHARACTERISTICS:

Clinical features of achondrogenesis type 1B (ACG1B) include extremely short limbs with short fingers and toes, hypoplasia of the thorax, protuberant abdomen, and hydropic fetal appearance caused by the abundance of soft tissue relative to the short skeleton. The face is flat, the neck is short, and the soft tissue of the neck may be thickened. Death occurs prenatally or shortly after birth.

DIAGNOSIS/TESTING:

The diagnosis of ACG1B rests on a combination of clinical, radiologic, and histopathologic features. SLC26A2 (DTDST) is the only gene in which mutation is known to cause ACG1B.

MANAGEMENT:

Treatment of manifestations: Palliative care for liveborn neonates.

GENETIC COUNSELING:

ACG1B is inherited in an autosomal recessive manner. At conception, each sib of a proband with ACG1B has a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Once an at-risk sib is known to be unaffected, the risk of his/her being a carrier is 2/3. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if both pathogenic alleles in the family are known and the carrier status of the parents has been confirmed. Ultrasound examination after 14-15 weeks’ gestation can be diagnostic.

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