Primordial dwarfism

Primordial dwarfism
Classification and external resources

Primordial dwarfism is a form of dwarfism that results in a smaller body size in all stages of life beginning from before birth.[1] 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 the gestational age, or as having intrauterine growth disability 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.

Most cases of short stature are caused by skeletal or endocrine disorders. The five subtypes of primordial dwarfism are among the most severe forms of the 200 types of dwarfism, and some sources estimate that there are only 100 individuals in the world with the disorder.[2] Other sources list the number of people currently afflicted as high as 100 in North America.

It is rare for individuals affected by primordial dwarfism to live past the age of 30.[3] In the case of microcephalic osteodysplastic primordial dwarfism (MOPD) type II there can be increased risk of vascular problems, which may cause premature death.[4]

Diagnosis

Since primordial dwarfism disorders are extremely rare, misdiagnosis is common. Because children with PD do not grow like other children, poor nutrition, a metabolic disorder, or a digestive disorder may be diagnosed initially. The correct diagnosis of PD may not be made until the child is 5 years old and it becomes apparent that the child has severe dwarfism.

Types

Name OMIM Description
Seckel Syndrome 210600 People with Seckel Syndrome are noted to have microcephaly. Many also suffer from scoliosis, hip dislocation, delayed bone age, radial head dislocation, and seizures. Mutations in patients with Seckel syndrome have recently been identified in the gene encoding centrosomal protein CEP152, which is also mutated in some cases of primary isolated microcephaly.
Osteodysplastic Primordial Dwarfism, Type I (ODPDI) 210710 This form of primordial dwarfism is often shortened to ODPDI. The corpus callosum of the brain is often undeveloped (called agenesis of the corpus callosum) and patients are known to have seizures and apnea. Hair thinness is also common, including scalp, hair, eyelashes and eyebrows. They suffer skeletally from short vertebrae, elongated clavicles, bent femora and hip displacement. Like those with Seckel Syndrome they also often have microcephaly.
Osteodysplastic Primordial Dwarfism, Type II (ODPDII) 210720 Those who have ODPDII often have additional medical problems as compared with the other types, such as a squeaky voice, microdontia, widely spaced primary teeth, poor sleep patterns (in early years), delayed mental development, frequent sickness, breathing problems, eating problems, hyperactivity, farsightedness, brain aneurysms, and do not respond to hormone therapy because primordial dwarfism is not caused by a lack of any growth hormone. After reviewing x-rays it is also found that many have dislocated joints, scoliosis, and delayed bone age as well as microcephaly. They will not reach the size of an average newborn until they are between the ages of 3-5.
Russell-Silver Syndrome 180860 The final height of those with Russell-Silver Syndrome often exceeds the height of others with primordial dwarfism, and they are very different. Some phenotypes (characteristics) of people who have Russell-Silver Syndrome are inadequate catch-up growth in first 2 years, body asymmetry, lack of appetite, low-set posteriorly rotated ears, clinodactly (inward curving) of the 5th finger, webbed toes, non-descended testicles (in males), weak muscle tone, delayed bone age, downturned corners of mouth & thin upper lip, hypospadias, high pitched voice, small chin, delayed closure of the fontanel, hypoglycemia, and a bossed forehead. Their heads may appear to be triangular shaped and large for their small body size.
Meier-Gorlin syndrome 224690 Individuals with Meier-Gorlin Syndrome often have small ears and no kneecaps. They are also found to have curved clavicles, narrow ribs, and elbow dislocation. Like Russel-Silver Syndrome, they usually exceed the height of those with Seckel Syndrome and ODPDI and II. It is also known as "ear, patella, short stature syndrome" (EPS). Mutations in patients with Meier-Gorlin syndrome have recently been identified in a series of genes involved in chromosomal replication, specifically in the pre-replication complex. Specific genes include origin recognition complex genes ORC1, ORC4 and ORC6, as well as other replication genes CDT1 and CDC6.

Causes and treatment

There are as yet no effective treatments for primordial dwarfism. It is known that PD is caused by inheriting a mutant gene from each parent.[5] The lack of normal growth in the disorder is not due to a deficiency of growth hormone, as in hypopituitary dwarfism. Administering growth hormone, therefore, has little or no effect on the growth of the individual with primordial dwarfism. In January 2008, it was published that mutations in the pericentrin gene (PCNT) were found to cause primordial dwarfism.[6] Pericentrin has a role in cell division, proper chromosome segregation, and cytokinesis.

Notable people believed to have primordial dwarfism

See also

References

  1. ↑ Fima Lifshitz (2007). Pediatric Endocrinology: Growth, adrenal, sexual, thyroid, calcium, and fluid balance disorders. CRC Press. pp. 15–. ISBN 978-1-4200-4270-2. Retrieved 7 January 2011.
  2. ↑ TLC :: TV Listings :: Daily Schedule
  3. ↑ As seen on the 2006 TLC/Channel Four program on primordial dwarfism, The Smallest People in the World,
  4. 1 2 American Journal of Medical Genetics
  5. ↑ National Geographic Channel Presents: Science of Dwarfism
  6. ↑ Rauch, A.; Thiel, C.T.; Schindler, D.; Wick, U.; Crow, Y.J.; Ekici, A.B.; Van Essen, A.J.; Goecke, T.O.; Al-gazali, L.; Chrzanowska, K.H.; et al. (2008). "Mutations in the Pericentrin (PCNT) Gene Cause Primordial Dwarfism". Science. 319 (5864): 816–9. PMID 18174396. doi:10.1126/science.1151174. Retrieved 2008-04-18.
  7. ↑ "72-year-old Nepalese man from remote mountain village declared shortest human on record". The Washington Post. Retrieved 2012-02-28.
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