Background DNA tandem repeats (TRs) are often abundant and occupy discrete regions in eukaryotic genomes. These TRs often cause or generate chromosomal rearrangements, which, in turn, drive chromosome evolution and speciation. Tracing the chromosomal distribution of TRs could therefore provide insights into the chromosome dynamics and speciation among closely related taxa. The basic chromosome number in the genus Senna is 2n = 28, but dysploid species like Senna tora have also been observed. Objective To understand the dynamics of these TRs and their impact on S. tora dysploidization. Methods We performed a comparative fluorescence in situ hybridization (FISH) analysis among nine closely related Senna species and compared the chromosomal distribution of these repeats from a cytotaxonomic perspective by using the ITS1-5.8S-ITS2 sequence to infer phylogenetic relationships. Results Of the nine S. tora TRs, two did not show any FISH signal whereas seven TRs showed similar and contrasting patterns to other Senna species. StoTR01_86, which was localized in the pericentromeric regions in all S. tora, but not at the nucleolar organizer region (NOR) site, was colocalized at the NOR site in all species except in S. siamea. StoTR02_7_tel was mostly localized at chromosome termini, but some species had an interstitial telomeric repeat in a few chromosomes. StoTR05_180 was distributed in the subtelomeric region in most species and was highly amplified in the pericentromeric region in some species. StoTR06_159 was either absent or colocalized in the NOR site in some species, and StoIGS_463, which was localized at the NOR site in S. tora, was either absent or localized at the subtelomeric or pericentromeric regions in other species. Conclusions These data suggest that TRs play important roles in S. tora dysploidy and suggest the involvement of 45S rDNA intergenic spacers in “carrying” repeats during genome reshuffling.

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Acromesomelic dysplasias are rare skeletal disorders leading to severe short stature and abnormal skeletal morphology. Acromesomelic dysplasia Maroteaux-type is caused by homozygous or compound heterozygous pathogenic variants in NPR2 that encodes for natriuretic peptide receptor B. Here, we reported the first AMDM case in South East Asia and identified a novel pathogenic variant in NPR2 (c. 152T>C, p. (Leu51Pro)). Further analyses reveal the parents and two other family members were heterozygous for the variant. The clinical report highlights the importance of molecular genetic testing in diagnosing rare hereditable disease affecting skeletal abnormalities. K E Y W O R D S acromesomelic dysplasia Maroteaux-type, short stature, NPR2, rare disease, skeletal disorder

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Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of rare genetic disorders, characterized by progressive weakness and muscle wasting. Currently, more than 27 different muscular disorders are identified as subtypes of LGMDs. Derived from the inheritance manners, LGMDs were classified into two main types: LGMD type 1 (autosomal dominant: AD) and LGMD type 2 (autosomal recessive: AR). 1 LGMD2 shows a more common distribution, with a prevalence of 1: 15,000, than LGMD1 (<10% of all LGMD cases). 2 Moreover, LGMD2 has been investigated to be associated with mutations from a group of sarcoglycanopathies genes such as SGCG, SGCA, SGCB, SGCD genes, which cause several subtypes of LGMD2 including LGMD2C to F, respectively.