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Very rare disorder characterized by extreme short-limbed dwarfism, lack of development of ribs, and other major bone formation. There are several subtypes of achondrogenesis. In general these forms are characterized by premature birth, fetal hydrops, normocephaly but an unusually soft cranial vault, and a short neck and trunk. Affected individuals have extremely short limbs, ribs, and vertebra. The disorder often is life-threatening either in utero or shortly after birth.

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Chondrogenesis Imperfecta; Hypochondrogenesis; Lethal Neonatal Dwarfism; Lethal Osteochondrodysplasia; Neonatal Dwarfism.

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Five subtypes of achondrogenesis have been described:

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  • Houston-Harris Type, achondrogenesis (type IA)
  • Parenti-Fraccaro Type, achondrogenesis (type IB)
  • Langer-Saldino Type, achondrogenesis (type II)
  • Achondrogenesis, Type III
  • Achondrogenesis, Type IV

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Achondrogenesis can be inherited as an autosomal or dominant recessive genetic trait. Achondrogenesis types IA, III, and IV are believed to be inherited as an autosomal recessive genetic trait. Achondrogenesis type IB is inherited as an autosomal recessive genetic trait with significant mutations in a gene called the diastrophic dysplasia/sulfate transporter gene. This gene encodes a sulfate transporter (DTDST). In addition, a deficiency in an enzyme responsible for the biologic activation of sulfate in children with type IB has been suggested. Achondrogenesis type II may be inherited by an autosomal recessive or dominant genetic trait. The possibility of mutations of the gene (COL2A1) encoding type II collagen has been suggested.

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There are several types of achondrogenesis. In general they are characterized by premature birth, fetal hydrops, normocephaly with cranial vault softness, and a short neck and trunk. Affected individuals have extremely short limbs, ribs, and vertebra, and other bones of the skeleton are not properly developed. Infants usually are born with a very prominent abdomen. Other features include a cleft palate, corneal clouding, ear deformities, and underdeveloped testicles and rectum.

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  • Achondrogenesis type I affects individuals with abnormally small or short bones in the arms and/or legs (micromelia). The patient's head is normal, but the calvarial plates may be unusually soft. The two subtypes of achondrogenesis type I are Houston-Harris type IA and Parenti-Fraccaro type IB. The Houston-Harris type is characterized by premature birth, fetal hydrops, and polyhydramnios. After birth, the affected infant usually manifests micrognathia, low-bridged nose, extreme short stature that is identifiable at birth, very short limbs (micromelia), lack of development of the bones of the spine, and an extremely short neck. The infant usually is stillborn or dies shortly after birth. The Parenti-Fraccaro type is characterized by the presence of thin ribs subjected to spontaneous fractures during manipulation at birth. The patient presents as a short-limbed dwarf in whom the important short stature and short limb disorder is easily identifiable at birth. The respiratory system often is affected by respiratory insufficiency resulting from pulmonary hypoplasia. The child is born prematurely and most often presents a fetal hydrops. The skeleton system is significantly affected with inappropriate development, especially of the spine, arms and legs. The infants ...

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