Molecular Analysis of the △F508
CFTR Gene Mutation Using
Polymerase Chain Reaction and
Restriction Fragment Profiling.
, Introduction with a Short Literature Review:
Cystic fibrosis (CF) is the most prevalent life-limiting autosomal recessive (BMS2115, Week 2, Mutations
& Genetic Disorders) germline disorder worldwide (BMS2115, Week 2, Mutations & Genetic Disorders),
characterised by defective epithelial fluid and electrolyte regulation that leads to chronic respiratory
infections, pancreatic insufficiency and progressive multisystem organ dysfunction (Ong and Ramsey,
2023).This disorder arises from mutations in the CF transmembrane conductance regulator (CFTR) gene,
which encodes a chloride ion channel critical for maintaining electrolyte balance across epithelial
membranes (Harris, 1992).
Of the more than 2,000 CFTR variants identified to date, the ∆F508 (F508del) mutation is the most
common and is strongly associated with severe clinical manifestations (Ong and Ramsey, 2023).
Molecular detection of ∆F508 is essential for early diagnosis, carrier screening and guiding appropriate
therapeutic interventions.
The ∆F508 mutation consists of a three-nucleotide deletion within exon 10 of the CFTR gene, leading to
the loss of a phenylalanine residue at position 508 (ClinVar, 2004). The mutation represents the loss of
the DNA triple TTC, this corresponds to the UUC codon for phenylalanine on the mRNA (Bartoszewski et
al., 2010). As three nucleotides are removed, the reading frame is maintained, producing an in-frame
deletion which removed phenylalanine at position 508 without changing downstream codons.
Mutations within this exon directly compromise the stability and intracellular trafficking of the
polypeptide. As ∆F508 is the most common pathogenic CFTR variant and alters a critical functional
domain, exon 10 serves as a primary target for molecular detection in diagnostic workflow. This deletion
disrupts the proper folding of the first nucleotide binding domain (NBD1), resulting in defective
processing and impaired trafficking of the CFTR protein to the epithelial cell membrane (Tzyh Chang
Hwang et al., 2023). The consequent reduction in functional chloride channels at the cell surface leads to
the features of CF, dehydrated airway surface fluid, thick mucus and recurrent bacterial infections.
Molecular insights confirm the mutation’s direct link to multisystem CF pathology (Ong and Ramsey,
2023) The CFTR gene, located on chromosome 7q31.2 and spanning roughly 189 kb (National Library of
Medicine, 2019), consists of 27 exons that encode a 1,480 amino-acid glycoprotein. This protein includes
two membrane-spanning domains, two nucleotide binding domains (NBD1 and NBD2) and a regulatory
domain (Tian et al., 2016). The ∆F508 mutation is situated within the NBD1 region, a domain essential
for ATP binding and channel gating. As the mutation arises from a three-base-pair deletion, targeted
molecular approaches such as polymerase chain reaction (PCR), restriction fragment length
polymorphism (RFLP) and DNA sequencing are particularly suited for its detection.
Molecular diagnostic workflows have developed CF genotyping. PCR allows selective amplification
(Navarro et al., 2015) of the CFTR exon 10 region, while RFLP analysis (Pourzand and Cerutti, 1993)
distinguishes the wild type and ∆F508 allele by exploiting the presence or absence of a restriction
enzyme recognition site altered by the mutation. These molecular methods offer rapid and sensitive
detection compared with older approaches, facilitating improved screening and management of CF.
CFTR Gene Mutation Using
Polymerase Chain Reaction and
Restriction Fragment Profiling.
, Introduction with a Short Literature Review:
Cystic fibrosis (CF) is the most prevalent life-limiting autosomal recessive (BMS2115, Week 2, Mutations
& Genetic Disorders) germline disorder worldwide (BMS2115, Week 2, Mutations & Genetic Disorders),
characterised by defective epithelial fluid and electrolyte regulation that leads to chronic respiratory
infections, pancreatic insufficiency and progressive multisystem organ dysfunction (Ong and Ramsey,
2023).This disorder arises from mutations in the CF transmembrane conductance regulator (CFTR) gene,
which encodes a chloride ion channel critical for maintaining electrolyte balance across epithelial
membranes (Harris, 1992).
Of the more than 2,000 CFTR variants identified to date, the ∆F508 (F508del) mutation is the most
common and is strongly associated with severe clinical manifestations (Ong and Ramsey, 2023).
Molecular detection of ∆F508 is essential for early diagnosis, carrier screening and guiding appropriate
therapeutic interventions.
The ∆F508 mutation consists of a three-nucleotide deletion within exon 10 of the CFTR gene, leading to
the loss of a phenylalanine residue at position 508 (ClinVar, 2004). The mutation represents the loss of
the DNA triple TTC, this corresponds to the UUC codon for phenylalanine on the mRNA (Bartoszewski et
al., 2010). As three nucleotides are removed, the reading frame is maintained, producing an in-frame
deletion which removed phenylalanine at position 508 without changing downstream codons.
Mutations within this exon directly compromise the stability and intracellular trafficking of the
polypeptide. As ∆F508 is the most common pathogenic CFTR variant and alters a critical functional
domain, exon 10 serves as a primary target for molecular detection in diagnostic workflow. This deletion
disrupts the proper folding of the first nucleotide binding domain (NBD1), resulting in defective
processing and impaired trafficking of the CFTR protein to the epithelial cell membrane (Tzyh Chang
Hwang et al., 2023). The consequent reduction in functional chloride channels at the cell surface leads to
the features of CF, dehydrated airway surface fluid, thick mucus and recurrent bacterial infections.
Molecular insights confirm the mutation’s direct link to multisystem CF pathology (Ong and Ramsey,
2023) The CFTR gene, located on chromosome 7q31.2 and spanning roughly 189 kb (National Library of
Medicine, 2019), consists of 27 exons that encode a 1,480 amino-acid glycoprotein. This protein includes
two membrane-spanning domains, two nucleotide binding domains (NBD1 and NBD2) and a regulatory
domain (Tian et al., 2016). The ∆F508 mutation is situated within the NBD1 region, a domain essential
for ATP binding and channel gating. As the mutation arises from a three-base-pair deletion, targeted
molecular approaches such as polymerase chain reaction (PCR), restriction fragment length
polymorphism (RFLP) and DNA sequencing are particularly suited for its detection.
Molecular diagnostic workflows have developed CF genotyping. PCR allows selective amplification
(Navarro et al., 2015) of the CFTR exon 10 region, while RFLP analysis (Pourzand and Cerutti, 1993)
distinguishes the wild type and ∆F508 allele by exploiting the presence or absence of a restriction
enzyme recognition site altered by the mutation. These molecular methods offer rapid and sensitive
detection compared with older approaches, facilitating improved screening and management of CF.
