Primordial dwarfism
A severe dwarfism disorder present from before birth.
Primordial dwarfism (PD) is a condition where a person is unusually small from before birth and throughout life. It describes a group of severe, proportionate dwarfism types where individuals are remarkably tiny for their age, even as fetuses. Diagnosis usually doesn't happen until a child is between three and five years old. Before that, doctors may see a fetus as small for its gestational age or detect intrauterine growth restriction on an ultrasound. People with PD are typically born with very low birth weights, and after birth, their growth remains far slower than normal, keeping them years behind their peers in both height and weight.
Most short stature cases come from skeletal or hormone problems, but PD is different. The five subtypes of PD are among the most extreme of the roughly 200 dwarfism types. There are currently no effective treatments, and while life expectancy varies by subtype, many individuals live well into adulthood—for instance, Jyoti Amge (born 1993) and many with MOPD type II have reached their 30s and beyond. In one subtype, microcephalic osteodysplastic primordial dwarfism type II (MOPDII), there's a higher risk of blood vessel issues that can lead to early death.
PD is caused by inheriting a mutated gene from each parent or by a new mutation in the fetus. The lack of growth isn't from a growth hormone deficiency, so giving growth hormone usually doesn't help—except in Russell–Silver syndrome (RSS), where children do respond well and may gain several inches if treated before puberty. In 2008, mutations in the pericentrin gene (PCNT) were found to cause MOPD type II; this gene helps with cell division, chromosome sorting, and cytokinesis. Other genes have been linked to rarer PD subtypes, but DNA2 mutations are not a widely recognized cause for the core PD subtypes described here.
Because PD disorders are extremely rare, misdiagnosis is common. Children may first be thought to have poor nutrition, a metabolic issue, or a digestive problem. The correct diagnosis often isn't made until age five, when the severe dwarfism becomes clear.
Quick Facts
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- Medical genetics
Facts from the source article.
Lore & Background
Primordial dwarfism (PD) is a form of dwarfism that results in a smaller body size in all stages of life beginning from before birth. More specifically, primordial dwarfism is a diagnostic category including specific types of profoundly proportionate dwarfism, in which individuals are extremely small for their age, even as a fetus. Most individuals with primordial dwarfism are not diagnosed until they are about 3–5 years of age. Medical professionals typically diagnose the fetus as being small for gestational age, or as showing intrauterine growth restriction when an ultrasound is conducted. Typically, people with primordial dwarfism are born with very low birth weights. After birth, growth continues at a much slower rate, leaving individuals with primordial dwarfism perpetually years behind their peers in stature and in weight.
Reader's Guide
Primordial dwarfism represents one of the most severe forms of dwarfism, with five subtypes among the 200 types of dwarfism. The condition is caused by inheriting a mutant gene from each parent or a mutation in the fetus, and is not due to a deficiency of growth hormone. Administering growth hormone has little or no effect, except in the case of Russell–Silver syndrome (RSS). In January 2008, mutations in the pericentrin gene (PCNT) were found to cause primordial dwarfism, and mutations in the DNA2 gene have been implicated in Seckel syndrome. Misdiagnosis is common because PD is extremely rare; poor nutrition, a metabolic disorder, or a digestive disorder may be diagnosed initially. The correct diagnosis may not be made until the child is 5 years old. There are as yet no effective treatments, and it is rare for individuals to live past the age of 30. In the case of microcephalic osteodysplastic primordial dwarfism type II (MOPDII), there can be increased risk of vascular problems, which may cause premature death. Notable cases include Jyoti Amge, the world's shortest woman since her 18th birthday on 16 December 2011, and Caroline Crachami, the first person recognized to have primordial dwarfism.
Did You Know?
- The five subtypes of primordial dwarfism are among the most severe forms of the 200 types of dwarfism.
- Administering growth hormone has little or no effect on growth in primordial dwarfism, except in the case of Russell–Silver syndrome (RSS).
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