Molecular genetics of human primary microcephaly: an overview
Abstract:
Autosomal recessive primary microcephaly (MCPH) is a neurodevelopmental disorder that is characterised by microcephaly present at birth and non-progressive mental retardation. Microcephaly is the outcome of a smaller but architecturally normal brain; the cerebral cortex exhibits a significant decrease in size. MCPH is a neurogenic mitotic disorder, though affected patients demonstrate normal neuronal migration, neuronal apoptosis and neural function. Twelve MCPH loci (MCPH1-MCPH12) have been mapped to date from various populations around the world and contain the following genes: Microcephalin, WDR62, CDK5RAP2, CASC5, ASPM, CENPJ, STIL, CEP135, CEP152, ZNF335, PHC1 and CDK6. It is predicted that MCPH gene mutations may lead to the disease phenotype due to a disturbed mitotic spindle orientation, premature chromosomal condensation, signalling response as a result of damaged DNA, microtubule dynamics, transcriptional control or a few other hidden centrosomal mechanisms that can regulate the number of neurons produced by neuronal precursor cells. Additional findings have further elucidated the microcephaly aetiology and pathophysiology, which has informed the clinical management of families suffering from MCPH. The provision of molecular diagnosis and genetic counselling may help to decrease the frequency of this disorder.
Insights
Autosomal recessive primary microcephaly (MCPH) is a rare brain development disorder. Genetic mutations affecting cell division cause reduced brain size and intellectual disability.
Area of Science:
- Neuroscience
- Genetics
- Developmental Biology
Background:
- Autosomal recessive primary microcephaly (MCPH) is a congenital neurodevelopmental disorder.
- Characterized by a smaller brain size (microcephaly) and non-progressive intellectual disability.
- MCPH is a neurogenic mitotic disorder affecting neuronal precursor cell proliferation.
Purpose of the Study:
- To review the genetic basis and pathophysiology of MCPH.
- To highlight the known MCPH genes and their potential roles in disease.
- To discuss the implications for clinical management and genetic counseling.
Main Methods:
- Literature review of MCPH genetic loci and associated genes.
- Analysis of proposed molecular mechanisms underlying MCPH.
- Synthesis of findings on etiology, pathophysiology, and clinical management.
Main Results:
- Twelve MCPH loci (MCPH1-MCPH12) have been identified, involving genes such as Microcephalin and ASPM.
- Mutations in these genes are predicted to disrupt mitotic spindle orientation, DNA damage response, or centrosomal functions.
- These disruptions lead to reduced neuron production and consequently, microcephaly.
Conclusions:
- Understanding MCPH genetics and pathophysiology aids in clinical management.
- Molecular diagnosis and genetic counseling are crucial for reducing MCPH incidence.
- Further research into centrosomal mechanisms may reveal novel therapeutic targets.
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