Genomic coordinate 9:120,388,875
Here I present: “Primary Microcephaly Type-3“, Victor McKusick, Mendelian Inheritance in Man’, 1966. (CDK5RAP2) 原發性小頭畸形。 icd10=Q02
INTRODUCTION.
Primary microcephaly (MCPH) refers to the clinical finding of a head circumference more than than 3 standard deviations (SD) below the age- and sex-related mean, present at birth. Primary microcephaly is a static developmental anomaly, distinguished from secondary microcephaly, which refers to a progressive neurodegenerative condition. Microcephaly is a disorder of fetal brain growth; individuals with microcephaly have small brains and almost always have impaired intellectual development, although rare individuals with mild microcephaly (-3 SD) and normal intelligence have been reported. Additional clinical features may include short stature or mild seizures. MCPH is associated with a simplification of the cerebral cortical gyral pattern and a slight reduction in the volume of the white matter, consistent with the small size of the brain, but the architecture of the brain in general is normal, with no evidence of a neuronal migration defect. Most cases of primary microcephaly show an autosomal recessive mode of inheritance. Because MCPH directly affects neurogenesis, or neurogenic mitosis, rather than growth of the skull, some prefer the term ‘microencephaly’.
There is evidence that primary microcephaly type-3 is caused by mutation in the cyclin-dependent kinase type-five (CDK5) regulatory subunit-associated protein-2 (CDK5RAP2) gene encoded on cytogenetic location 9q33.2 and genomic coordinate 9:120,388,875. The CDK5RAP2 gene encodes a centrosomal protein that localizes to the spindle poles during mitosis. CDK5 regulatory subunit-associated protein-2 is a protein that in humans is encoded by the CDK5RAP2 gene that has necessary roles in the formation and stability of microtubules from the centromere and has been found to be linked to human brain size variation.
