Expanding MNS1 Heterotaxy Phenotype

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• The meiosis-specific nuclear structural protein-1 gene (MNS1) is crucial for motile ciliary function and sperm flagella assembly.
• Previous studies linked homozygous MNS1 variants to autosomal recessive visceral heterotaxy.

Observation:

• A French individual presented with compound heterozygous MNS1 variants, complete situs inversus, severe myopia, and dental agenesis.
• Further investigation identified a family with sibling fetuses exhibiting homozygous in-frame deletion variants in MNS1 and homozygous missense variants in GLDN.
• Autopsies of the fetuses revealed a complex prenatal malformation syndrome.

Findings:

• This study reports new cases of MNS1-related disorder, identifying compound heterozygous and homozygous variants in MNS1.
• The identified variants include frameshift, nonsense, in-frame deletion, and missense mutations.
• The findings expand the spectrum of MNS1 variants associated with visceral heterotaxy and complex malformations.

Implications:

• These findings broaden the clinical and genetic understanding of MNS1-related disorders.
• The identification of novel variants aids in diagnosing rare genetic conditions involving cilia and embryonic development.
• This research highlights the importance of genetic analysis in cases of complex congenital malformations and situs abnormalities.