The 1.4-Mb CMT1A Duplication/HNPP Deletion Genomic Region Reveals Unique Genome Architectural Features and Provides Insights into the Recent Evolution of New Genes
Overview
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Duplication and deletion of the 1.4-Mb region in 17p12 that is delimited by two 24-kb low copy number repeats (CMT1A-REPs) represent frequent genomic rearrangements resulting in two common inherited peripheral neuropathies, Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsy (HNPP). CMT1A and HNPP exemplify a paradigm for genomic disorders wherein unique genome architectural features result in susceptibility to DNA rearrangements that cause disease. A gene within the 1.4-Mb region, PMP22, is responsible for these disorders through a gene-dosage effect in the heterozygous duplication or deletion. However, the genomic structure of the 1.4-Mb region, including other genes contained within the rearranged genomic segment, remains essentially uncharacterized. To delineate genomic structural features, investigate higher-order genomic architecture, and identify genes in this region, we constructed PAC and BAC contigs and determined the complete nucleotide sequence. This CMT1A/HNPP genomic segment contains 1,421,129 bp of DNA. A low copy number repeat (LCR) was identified, with one copy inside and two copies outside of the 1.4-Mb region. Comparison between physical and genetic maps revealed a striking difference in recombination rates between the sexes with a lower recombination frequency in males (0.67 cM/Mb) versus females (5.5 cM/Mb). Hypothetically, this low recombination frequency in males may enable a chromosomal misalignment at proximal and distal CMT1A-REPs and promote unequal crossing over, which occurs 10 times more frequently in male meiosis. In addition to three previously described genes, five new genes (TEKT3, HS3ST3B1, NPD008/CGI-148, CDRT1, and CDRT15) and 13 predicted genes were identified. Most of these predicted genes are expressed only in embryonic stages. Analyses of the genomic region adjacent to proximal CMT1A-REP indicated an evolutionary mechanism for the formation of proximal CMT1A-REP and the creation of novel genes by DNA rearrangement during primate speciation.
Laudanski K, Elmadhoun O, Mathew A, Kahn-Pascual Y, Kerfeld M, Chen J Healthcare (Basel). 2024; 12(8).
PMID: 38667620 PMC: 11050561. DOI: 10.3390/healthcare12080858.
Yoshioka Y, Taniguchi J, Homma H, Tamura T, Fujita K, Inotsume M Commun Med (Lond). 2023; 3(1):170.
PMID: 38017287 PMC: 10684506. DOI: 10.1038/s43856-023-00400-y.
Yu T, Zhang T, Zhao L, Li K, Li J, Yu A Medicine (Baltimore). 2023; 102(31):e34602.
PMID: 37543771 PMC: 10403009. DOI: 10.1097/MD.0000000000034602.
Pennings M, Meijer R, Gerrits M, Janssen J, Pfundt R, de Leeuw N Eur J Hum Genet. 2023; 31(6):654-662.
PMID: 36781956 PMC: 10250492. DOI: 10.1038/s41431-023-01312-0.
Biology in balance: human diploid genome integrity, gene dosage, and genomic medicine.
Lupski J Trends Genet. 2022; 38(6):554-571.
PMID: 35450748 PMC: 9222541. DOI: 10.1016/j.tig.2022.03.001.