Encyclopedia
Meier-Gorlin syndrome is a condition primarily characterized by short stature.
- genetic conditions
1. Introduction
It is considered a form of primordial dwarfism because the growth problems begin before birth (intrauterine growth retardation). After birth, affected individuals continue to grow at a slow rate. Other characteristic features of this condition are underdeveloped or missing kneecaps (patellae), small ears, and, often, an abnormally small head (microcephaly). Despite a small head size, most people with Meier-Gorlin syndrome have normal intellect.
Some people with Meier-Gorlin syndrome have other skeletal abnormalities, such as unusually narrow long bones in the arms and legs, a deformity of the knee joint that allows the knee to bend backwards (genu recurvatum), and slowed mineralization of bones (delayed bone age).
Most people with Meier-Gorlin syndrome have distinctive facial features. In addition to being abnormally small, the ears may be low-set or rotated backward. Additional features can include a small mouth (microstomia), an underdeveloped lower jaw (micrognathia), full lips, and a narrow nose with a high nasal bridge.
Abnormalities in sexual development may also occur in Meier-Gorlin syndrome. In some males with this condition, the testes are small or undescended (cryptorchidism). Affected females may have unusually small external genital folds (hypoplasia of the labia majora) and small breasts. Both males and females with this condition can have sparse or absent underarm (axillary) hair.
Additional features of Meier-Gorlin syndrome can include difficulty feeding and a lung condition known as pulmonary emphysema or other breathing problems.
2. Frequency
Meier-Gorlin syndrome is a rare condition; however, its prevalence is unknown.
3. Causes
Meier-Gorlin syndrome can be caused by mutations in one of several genes. Each of these genes, ORC1, ORC4, ORC6, CDT1, and CDC6, provides instructions for making one of a group of proteins known as the pre-replication complex. This complex regulates initiation of the copying (replication) of DNA before cells divide. Specifically, the pre-replication complex attaches (binds) to certain regions of DNA known as origins of replication, allowing copying of the DNA to begin at that location. This tightly controlled process, called replication licensing, helps ensure that DNA replication occurs only once per cell division and is required for cells to divide.
Mutations in any one of these genes impair formation of the pre-replication complex and disrupt replication licensing; however, it is not clear how a reduction in replication licensing leads to Meier-Gorlin syndrome. Researchers speculate that such a reduction delays the cell division process, which impairs growth of the bones and other tissues during development. Some research suggests that some of the pre-replication complex proteins have additional functions, impairment of which may contribute to features of Meier-Gorlin syndrome, such as delayed development of the kneecaps and ears.
54. Inheritance
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
65. Other Names for This Condition
- ear, patella, short stature syndrome
- microtia, absent patellae, micrognathia syndrome
References
- Bicknell LS, Bongers EM, Leitch A, Brown S, Schoots J, Harley ME, Aftimos S,Al-Aama JY, Bober M, Brown PA, van Bokhoven H, Dean J, Edrees AY, Feingold M,Fryer A, Hoefsloot LH, Kau N, Knoers NV, Mackenzie J, Opitz JM, Sarda P, Ross A, Temple IK, Toutain A, Wise CA, Wright M, Jackson AP. Mutations in thepre-replication complex cause Meier-Gorlin syndrome. Nat Genet. 2011 Feb27;43(4):356-9. doi: 10.1038/ng.775.
- Bicknell LS, Walker S, Klingseisen A, Stiff T, Leitch A, Kerzendorfer C,Martin CA, Yeyati P, Al Sanna N, Bober M, Johnson D, Wise C, Jackson AP,O'Driscoll M, Jeggo PA. Mutations in ORC1, encoding the largest subunit of theorigin recognition complex, cause microcephalic primordial dwarfism resemblingMeier-Gorlin syndrome. Nat Genet. 2011 Feb 27;43(4):350-5. doi: 10.1038/ng.776.
- de Munnik SA, Bicknell LS, Aftimos S, Al-Aama JY, van Bever Y, Bober MB,Clayton-Smith J, Edrees AY, Feingold M, Fryer A, van Hagen JM, Hennekam RC,Jansweijer MC, Johnson D, Kant SG, Opitz JM, Ramadevi AR, Reardon W, Ross A,Sarda P, Schrander-Stumpel CT, Schoots J, Temple IK, Terhal PA, Toutain A, WiseCA, Wright M, Skidmore DL, Samuels ME, Hoefsloot LH, Knoers NV, Brunner HG,Jackson AP, Bongers EM. Meier-Gorlin syndrome genotype-phenotype studies: 35individuals with pre-replication complex gene mutations and 10 without molecular diagnosis. Eur J Hum Genet. 2012 Jun;20(6):598-606. doi: 10.1038/ejhg.2011.269.
- de Munnik SA, Otten BJ, Schoots J, Bicknell LS, Aftimos S, Al-Aama JY, vanBever Y, Bober MB, Borm GF, Clayton-Smith J, Deal CL, Edrees AY, Feingold M,Fryer A, van Hagen JM, Hennekam RC, Jansweijer MC, Johnson D, Kant SG, Opitz JM, Ramadevi AR, Reardon W, Ross A, Sarda P, Schrander-Stumpel CT, Sluiter AE, TempleIK, Terhal PA, Toutain A, Wise CA, Wright M, Skidmore DL, Samuels ME, HoefslootLH, Knoers NV, Brunner HG, Jackson AP, Bongers EM. Meier-Gorlin syndrome: growth and secondary sexual development of a microcephalic primordial dwarfism disorder.Am J Med Genet A. 2012 Nov;158A(11):2733-42. doi: 10.1002/ajmg.a.35681.
- Guernsey DL, Matsuoka M, Jiang H, Evans S, Macgillivray C, Nightingale M,Perry S, Ferguson M, LeBlanc M, Paquette J, Patry L, Rideout AL, Thomas A, Orr A,McMaster CR, Michaud JL, Deal C, Langlois S, Superneau DW, Parkash S, Ludman M,Skidmore DL, Samuels ME. Mutations in origin recognition complex gene ORC4 cause Meier-Gorlin syndrome. Nat Genet. 2011 Feb 27;43(4):360-4. doi: 10.1038/ng.777.
