What does the name mean?
Primordial has been defined as belonging to or being characteristic of the earliest stages of development of an organism. Therefore, Primordial Dwarfism is a class of disorders where growth delay occurs at the earliest stages of development. Unlike some of the other forms of dwarfism where newborn infants can have average lengths, children with Primordial Dwarfism are born smaller than average and have intrauterine growth retardation (IUGR).
What conditions make up the class of primordial dwarfism?
Unlike some of the other conditions described on this website, primordial dwarfism is not a specific diagnosis.
It is in fact a class of disorders to which at least 5 different conditions are currently grouped:
- Russell-Silver syndrome
- Seckel syndrome
- Meier-Gorlin syndrome
- Majewski osteodysplastic primordial dwarfism (MOPD) Types I/III
- MOPD Type II
The Russell-Silver, Seckel and Meier-Gorlin syndromes are relatively well defined entities and we will not discuss them here.
We will limit our discussion to MOPD Type II. Most of the information below can be examined in more detail in Hall et. al (1).
How common is primordial dwarfism?
All of the conditions are quite rare and very little is known concerning the incidences. For MOPD Type II, we estimate that there are no more than 100 patients in the United States and Canada giving a rough estimate of 1 in 3 million.
Is MOPD Type II inherited?
Yes, it is genetic. MOPDII has an autosomal recessive pattern. This means that the genetic information from both parents was necessary for the child to have this condition. It also means that parents of children with MOPDII have a 25% chance with each pregnancy of having another child with MOPDII.
What causes MOPD Type II ?
Everyone has two copies of a gene called pericentrin (PCNT). MOPDII results when there is a gene change (mutation) in each copy of an individual’s pericentrin gene, causing both copies to be nonfunctional. (2)