MICROCEPHALY - SCI &
TECH
News: How an altered protein and
fussy neurons conspire to cause microcephaly
What's in the news?
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A gene called SASS6
(Spindle Assembly Abnormal Protein 6) and its variants have been found to play
a key role in a developmental process that causes “Microcephaly”.
Microcephaly:
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Microcephaly is a condition where a baby’s head is much smaller than normal.
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It is associated with a smaller brain, poor motor
skills, poor speech, abnormal facial features, and intellectual disabilities.
Developmental Roots:
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The condition is believed to start during the peak phase of brain development in the
embryo.
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Cells that are supposed to become neurons fail to
divide normally.
Diagnosis:
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Microcephaly can be diagnosed before birth using foetal ultrasound and MRI.
Study on Roles of SASS6
Gene:
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Since 2014, the SASS6 gene and its variants have
been linked to microcephaly.
Recent Study in China:
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The study of a consanguine
couple revealed microcephaly and fetal growth issues.
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Confirming the SASS6 gene’s role in microcephaly,
findings suggest embryo survival requires at least one functional gene copy.
University of Cologne
Study:
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Researchers removed all functional SASS6 genes from
mouse embryo-derived cells.
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Even without the genes, cells could make abnormal
but passable centrioles (structures needed for cell division).
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When these cells were prompted to become neurons,
the centrioles disappeared, preventing the cells from becoming neurons.
Consanguinity and
Genetic Risk of Microcephaly:
Expert Insight:
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Researchers explained that over 70% of congenital microcephaly cases come
from consanguineous marriages.
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Such marriages increase the risk of inheriting
mutated genes from both parents.
Genetic Causes:
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Mutations in 30 genes cause microcephaly.
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10 of these genes create proteins needed for
centrioles, which are crucial for cell division.
Gene Suppression in C.
elegans:
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Suppressing the SASS6 gene halted new centriole
assembly, stopping development.
2014 Study on a
Pakistani Family:
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Researchers found four family members with
microcephaly due to the Ile62Thr
mutation in the SASS6 gene.
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The Ile62Thr mutation was introduced into the C.
elegans SASS6 gene.
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The mutation alone did not significantly impair
centriole function but became deadly when combined with another mutation.
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In humans, this mutation causes microcephaly due to
its impact on centriole function.