Preimplantation Genetic Testing of Spinocerebellar Ataxia Type 3/Machado-Joseph Disease-Robust Tools for Direct and Indirect Detection of the ATXN3 (CAG) n Repeat Expansion

• Published in: International journal of molecular sciences Vol. 25; no. 15; p. 8073
• Main Authors: Lian, Mulias, Tan, Vivienne J, Taguchi, Riho, Zhao, Mingjue, Phang, Gui-Ping, Tan, Arnold S, Liu, Shuling, Lee, Caroline G, Chong, Samuel S
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 24.07.2024
• Subjects: Alleles; Ataxia; Ataxin-3 - genetics; Biopsy; Embryos; Female; Genetic testing; Genetic Testing - methods; Genomes; Genotype; Haplotypes; Humans; In vitro fertilization; Machado-Joseph Disease - diagnosis; Machado-Joseph Disease - genetics; Male; Microsatellite Repeats - genetics; multi-microsatellite haplotyping; Polymorphism; Pregnancy; Preimplantation Diagnosis - methods; preimplantation genetic testing for monogenic disorders; Repressor Proteins; spinocerebellar ataxia type 3/Machado–Joseph disease; Trinucleotide Repeat Expansion - genetics; triplet-primed PCR; White people; multi-microsatellite haplotyping; triplet-primed PCR; preimplantation genetic testing for monogenic disorders; spinocerebellar ataxia type 3/Machado–Joseph disease
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25158073

Spinocerebellar ataxia type 3/Machado-Joseph disease (SCA3/MJD) is a neurodegenerative disorder caused by the CAG repeat expansion. Preimplantation genetic testing for monogenic disorders (PGT-M) of SCA3/MJD should include reliable repeat expansion detection coupled with high-risk allele determination using informative linked markers. One couple underwent SCA3/MJD PGT-M combining (CAG) triplet-primed PCR (TP-PCR) with customized linkage-based risk allele genotyping on whole-genome-amplified trophectoderm cells. Microsatellites closely linked to were identified and 16 markers were genotyped on 187 anonymous DNAs to verify their polymorphic information content. In the SCA3/MJD PGT-M case, the (CAG) TP-PCR and linked marker analysis results concurred completely. Among the three unaffected embryos, a single embryo was transferred and successfully resulted in an unaffected live birth. A total of 139 microsatellites within 1 Mb upstream and downstream of the CAG repeat were identified and 8 polymorphic markers from each side were successfully co-amplified in a single-tube reaction. A PGT-M assay involving (CAG) TP-PCR and linkage-based risk allele identification has been developed for SCA3/MJD. A hexadecaplex panel of highly polymorphic microsatellites tightly linked to has been developed for the rapid identification of informative markers in at-risk couples for use in the PGT-M of SCA3/MJD.