Achondrogenesis (Type-1B)

Definition

Definition of Achondrogenesis (Type-1B)
Achondrogenesis (Type-1B) is characterized by extremely short limbs, a narrow chest, and a prominent, rounded abdomen. The fingers and toes are short and the feet may be rotated inward. Affected infants frequently have a soft out-pouching around the belly-button (an umbilical hernia) or near the groin (an inguinal hernia).

Achondrogenesis (Type-1B) is a rare genetic disorder; its incidence is unknown. Achondrogenesis, type 1B is the most severe condition in a spectrum of skeletal disorders caused by mutations in the SLC26A2 gene. This gene provides instructions for making a protein that is essential for the normal development of cartilage and for its conversion to bone. Mutations in the SLC26A2 gene disrupt the structure of developing cartilage, preventing bones from forming properly and resulting in the skeletal problems characteristic of achondrogenesis, type 1B.

Achondrogenesis (Type-1B) is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

Symptoms

Symptoms of Achondrogenesis (Type-1B)
The list of medical symptoms mentioned in various sources for Achondrogenesis type 1B include those below. Note that Achondrogenesis (Type-1B) symptoms usually refers to various medical symptoms known to a patient, but the phrase Achondrogenesis (Type-1B) signs may often refer to those signs that are only noticable by a doctor:

1. Extremely Small Stature
2. Large Head
3. Low Nasal Bridge
4. Small Lower Jaw
5. Severe Micromelia
6. Poor Bone Formation of Skull
7. Poor Bone Formation of Vertebra
8. Poor Bone Formation of Fibula

Causes

Causes of Achondrogenesis (Type-1B)
Type IB is an autosomal recessive disorder resulting from mutations of the diastrophic dysplasia sulfate transporter (DDST) gene (SLC26A2), which is located at 5q32-q33.

Diagnosis

Diagnosis of Achondrogenesis (Type-1B)
The diagnosis of ACG1B rests upon a combination of clinical, radiologic, and histopathologic features. SLC26A2(DTDST) is the only gene known to be associated with AO2. The diagnosis can be confirmed by molecular genetic testing of SLC26A2, which is clinically available. Sulfate incorporation assay in cultured skin fibroblasts (or chondrocytes) is possible in rare cases in which molecular genetic testing fails to identify SLC26A2 mutations.

Complications

Complications of Achondrogenesis (Type-1B)
The list of complications that have been mentioned in various sources for Achondrogenesis type 1B includes:

1. Stillbirth
2. Neonatal death

Treatment

Treatment of Achondrogenesis (Type-1B)
There is no specific treatment for this disorder.