Handedness and situs inversus in primary ciliary dyskinesia

Area of Science:

• Developmental Biology
• Human Genetics
• Medical Research

Background:

• Primary ciliary dyskinesia (PCD) is a genetic disorder affecting cilia function.
• Fifty percent of individuals with PCD exhibit situs inversus, a condition where major visceral organs are reversed.
• Situs inversus is often attributed to impaired nodal ciliary rotation and subsequent failure in symmetry breaking during embryonic development.

Purpose of the Study:

• To investigate the role of nodal cilia in establishing body symmetry.
• To determine if cerebral lateralization is affected in individuals with primary ciliary dyskinesia and situs inversus.
• To explore potential alternative mechanisms responsible for symmetry breaking.

Main Methods:

• A study was conducted involving 88 individuals diagnosed with primary ciliary dyskinesia.
• Participants were assessed for the presence of situs inversus or situs solitus.
• Handedness was recorded for all participants to evaluate cerebral lateralization.

Main Results:

• In a cohort of 88 PCD patients, 46 had situs inversus and 42 had situs solitus.
• Left-handedness was observed in 15.2% of individuals with situs inversus and 14.3% of those with situs solitus.
• Cerebral lateralization, indicated by handedness, was present in both situs inversus and situs solitus groups.
• Wearing a wristwatch on the right wrist showed a correlation with situs inversus.

Conclusions:

• The persistence of cerebral lateralization in PCD patients with situs inversus indicates that nodal cilia are not the primary determinants of vertebrate body symmetry.
• Alternative mechanisms likely contribute to the establishment of body asymmetry.
• Behavioral lateralization, such as wristwatch preference, may be linked to situs inversus in PCD.