TMEM16A deficiency: a potentially fatal neonatal disease resulting from impaired chloride currents

Area of Science:

• Genetics
• Molecular Biology
• Physiology

Background:

• TMEM16A (ANO1) is a calcium-activated chloride channel crucial for secretory epithelia function.
• Mutations in TMEM16A can lead to severe gastrointestinal disorders.
• Two siblings presented with early-onset intestinal dysfunction.

Purpose of the Study:

• To investigate the genetic basis of a rare secretory disorder in two siblings.
• To characterize the functional consequences of a novel TMEM16A variant on ion transport.
• To explore the relationship between TMEM16A dysfunction and CFTR activity.

Main Methods:

• Exome sequencing to identify pathogenic variants.
• Reverse transcription PCR, Western blot, and immunohistochemistry for expression analysis.
• Electrophysiological and cell biological studies in patient cells and HEK293 transfectants.

Main Results:

• A homozygous truncating pathogenic variant in ANO1 (encoding TMEM16A) was identified.
• The variant abolished calcium-activated chloride currents mediated by TMEM16A.
• Secondary impairment of CFTR function was observed without causing cystic fibrosis.

Conclusions:

• TMEM16A deficiency is a serious disorder resulting from loss of calcium-activated chloride currents.
• Impaired TMEM16A function affects CFTR activity, with potential implications for cystic fibrosis treatment strategies.
• Understanding TMEM16A's role is critical for diagnosing and potentially treating related secretory disorders.