ACHONDROGENESIS 

 

 Achondrogenesis Type I (Parenti-Fraccaro)



  • Autosomal Recessive. Most severe type.
  • Defective endochondral and intramembranous ossification.
  • Lack of ossification in the calvarium, spine and pelvis.
  • Absent sacrum and pubic bone
  • Severe micromelia. Short long bones (radius, femur and especially ulna) without bowing.
  • Thin ribs with multiple fractures and flared anterior ends.
  • Small thorax with a protuberant abdomen.
  • Associated malformations include urinary tract duplication, hydronephrosis, cleft palate, ear deformities, corneal clouding and blue sclera, anal atresia and aplastic testis.

 

Postnatal Speciman

 

Postnatal Xray

 

 

 

 

Video clip of Achondrogenesis type I

 

 

 

 

   Achondrogenesis Type II (Langer-Saldino)


 

  • Defective endochondral ossification only.
  • Normal cranial vault ossification differentiates it from type I and osteogenesis imperfecta type II.
  • No ossification of the lower lumbar vertebrae or sacrum.
  • Ribs are short and horizontal without fractures.
  • Irregular flaring of the metaphysis, especially the humerus.
  • Redundant soft tissues with subcutaneous edema (hydrops).
  • Cystic hygroma / Increased nuchal translucency.
  • Polyhydramnios.
  • Lethal in utero or soon after birth.
  • Differential diagnosis - Thanatophoric dwarf.
  • Most cases are sporadic (new autosomal dominant mutation) (5).

 

 

 

Video clip of Achondrogenesis Type 2

 

 

 

 

DIFFERENTIAL DIAGNOSIS

 

  • Grebe syndrome.
  • Thanatophoric dysplasia.
  • Atelosteogenesis type II.
  • Hypophosphatasia.

 

ASSOCIATIONS

 

There have been two reports of an association between Achondrogenesis type I and II and cystic hygroma (6,7). 

 

 

ULTRASOUND
  1. Benacerraf B, Osathanondh R, Bieber FR. Achondrogenesis type I: Ultrasound diagnosis in utero. J Clin Ultrasound 1984;12:357-359.
  2. Wenstrom KD, Williamson RA, Hoover WW et.al. Achondrogenesis type II (Langer-Saldino) in association with jugular lymphatic obstruction sequence. Prenat Diagn 1989;9:527-532.
  3. Rottem S, Bronshtein M, Thaler I et.al. First trimester transvaginal sonographic diagnosis of fetal anomalies. Lancet 1989;i:444-445.
  4. Fisk NM, Vaughan J, Smidt M et.al. Transvaginal ultrasound recognition of nuchal edema in the first trimester diagnosis of achondrogenesis. J Clin Ultrasound 1991;19:586-590.
  5. Knowlton S, Graves C, Tiller GE. Achondrogenesis. Fetus 1992;2:7564.
  6. Wenstrom KD, Williamson RA, Hoover WW et.al. Achondrogenesis type II in association with jugular lymphatic obstruction sequence. Prenat Diagn 1989;9:527-532.
  7. Ozeren S, Yuksel A, Tukel T. Prenatal sonographic diagnosis of type I achondrogenesis with a large cystic hygroma. Ultrasound Obstet Gynecol 1999;13:75-76.