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Classification according to ICD-10
Q77.8 Other osteochondrodysplasias with growth disorders of the long bones and the spine
ICD-10 online (WHO version 2019)

Pseudoachondroplasia is a congenital form of short stature that is characterized by short limbs. It belongs to the skeletal dysplasias and is reminiscent of achondroplasia .

Synonyms: Pseudoachrondroplastic form of spondyloepiphyseal dysplasia ; English Pseudoachondroplastic Dysplasia; PSACH

The first differentiation from spondyloepiphyseal dysplasia was made in 1959 by pediatricians and human geneticists Pierre Maroteaux and Maurice Lamy (1895–1975).


The frequency is given as 1 in 30–60,000, inheritance is autosomal dominant . Most diseases occur in isolation as a new mutation .

Autosomal dominant inheritance means that a person with pseudoachondroplasia has a 50 percent or 1 to 1 risk of having children with pseudoachondroplasia with a normal-sized partner (according to Mendel's rule ).

root cause

The disease are mutations in the COMP gene at the locus 19p13.11 based encoding the 'cartilage oligomeric matrix protein'.

Clinical manifestations

The main clinical criteria are:

possibly kyphoscoliosis

At first these children grow normally, but by the age of two to three years it becomes apparent that a child is late in walking and developing a waddling gait, which often leads to this diagnosis. The child's growth gradually slows down in the following years. As the rate of growth slows down, the torso appears with lumbar lordosis and a rhizome-like shortening of the limbs. The final height of an adult is 80–130 cm. A growth curve for individuals with pseudoachondroplasia is available (from the Greenberg Center for Skeletal Dysplasias). A copy of a child's individual growth curve would be helpful to a pediatrician.

Individuals with pseudoachondroplasia have normal head sizes and facial structures. The characteristic waddling gait is due to the inclusion of the hip when walking. The legs are not aligned in the same direction and can exhibit a variety of deformations such as: B. bow or saber legs ( genu varum ), knock knees ( genu valgum ), and other mixed deformations (bow leg on one side and knock knees on the other). Joint hypermobility can be observed, especially in the wrists and fingers, but the elbow extensibility is often limited. The hands and feet themselves are rather short. Osteoarthritis occurs in early adulthood, especially in weight-bearing joints.


The diagnosis is often not suspected at birth, but only in the toddler at the age of two to three years. The diagnosis is confirmed with the help of the X-ray image . Criteria are:

Differential diagnosis

The following are to be distinguished:


  • KL Posey, JL Alcorn, JT Hecht: Pseudoachondroplasia / COMP - translating from the bench to the bedside. In: Matrix biology: Journal of the International Society for Matrix Biology. Vol. 37, July 2014, pp. 167-173, doi: 10.1016 / j.matbio.2014.05.006 , PMID 24892720 , PMC 4209947 (free full text) (review).

Web links

  • MD Briggs, MJ Wright: Pseudoachondroplasia. in: GeneReviews , PMID 20301660
  • Greenberg Center for Skeletal Dysplasias

Individual evidence

  1. a b c Bernfried Leiber (founder): The clinical syndromes. Syndromes, sequences and symptom complexes . Ed .: G. Burg, J. Kunze, D. Pongratz, PG Scheurlen, A. Schinzel, J. Spranger. 7., completely reworked. Edition. tape 2 : symptoms . Urban & Schwarzenberg, Munich et al. 1990, ISBN 3-541-01727-9 .
  2. a b c d pseudoachondroplasia. In: Orphanet (Rare Disease Database).
  3. M. Lamy, P. Maroteaux: Le nanisme diastrophique. In: La Presse médicale. Vol. 68, November 1960, pp. 1977-1980, PMID 13758600 .
  4. ^ Genetics Home Reference
  5. Pseudoachondroplasia.  In: Online Mendelian Inheritance in Man . (English)
  6. E. Délot et al.: Trinucleotide expansion mutations in the cartilage oligomeric matrix protein (COMP) gene . In: Hum Mol Genet . 1999 Jan; 8 (1), pp. 123-128. PMID 9887340
  7. a b c F. Hefti: Pediatric orthopedics in practice. Springer 1998, p. 659, ISBN 3-540-61480-X .