Characterizing the morbid genome of ciliopathies

Background Ciliopathies are clinically diverse disorders of the primary cilium. Remarkable progress has been made in understanding the molecular basis of these genetically heterogeneous conditions; however, our knowledge of their morbid genome, pleiotropy, and variable expressivity remains incomplete. Results We applied genomic approaches on a large patient cohort of 371 affected individuals from 265 families, with phenotypes that span the entire ciliopathy spectrum. Likely causal mutations in previously described ciliopathy genes were identified in 85% (225/265) of the families, adding 32 novel alleles. Consistent with a fully penetrant model for these genes, we found no significant difference in their “mutation load” beyond the causal variants between our ciliopathy cohort and a control non-ciliopathy cohort. Genomic analysis of our cohort further identified mutations in a novel morbid gene TXNDC15, encoding a thiol isomerase, based on independent loss of function mutations in individuals with a consistent ciliopathy phenotype (Meckel-Gruber syndrome) and a functional effect of its deficiency on ciliary signaling. Our study also highlighted seven novel candidate genes (TRAPPC3, EXOC3L2, FAM98C, C17orf61, LRRCC1, NEK4, and CELSR2) some of which have established links to ciliogenesis. Finally, we show that the morbid genome of ciliopathies encompasses many founder mutations, the combined carrier frequency of which accounts for a high disease burden in the study population. Conclusions Our study increases our understanding of the morbid genome of ciliopathies. We also provide the strongest evidence, to date, in support of the classical Mendelian inheritance of Bardet-Biedl syndrome and other ciliopathies

Molecular autopsy in maternal-fetal medicine

Purpose: The application of genomic sequencing to investigate unexplained death during early human development, a form of lethality likely enriched for severe Mendelian disorders, has been limited.& para;& para;Methods: In this study, we employed exome sequencing as a molecular autopsy tool in a cohort of 44 families with at least one death or lethal fetal malformation at any stage of in utero development. Where no DNA was available from the fetus, we performed molecular autopsy by proxy, i.e., through parental testing.& para;& para;Results: Pathogenic or likely pathogenic variants were identified in 22 families (50%), and variants of unknown significance were identified in further 15 families (34%). These variants were in genes known to cause embryonic or perinatal lethality (ALPL, GUSB, SLC17A5, MRPS16, THSD1, PIEZO1, and CTSA), genes known to cause Mendelian phenotypes that do not typically include embryonic lethality (INVS, FKTN, MYBPC3, COL11A2, KRIT1, ASCC1, NEB, LZTR1, TTC21B, AGT, KLHL41, GFPT1, and WDR81) and genes with no established links to human disease that we propose as novel candidates supported by embryonic lethality of their orthologs or other lines of evidence (MS4A7, SERPINA11, FCRL4, MYBPHL, PRPF19, VPS13D, KIAA1109, MOCS3, SVOPL, FENI, HSPB11, KIF19, and EXOC3L2).& para;& para;Conclusion: Our results suggest that molecular autopsy in pregnancy losses is a practical and high-yield alternative to traditional autopsy, and an opportunity for bringing precision medicine to the clinical practice of perinatology

Additional file 3: of Characterizing the morbid genome of ciliopathies

Supplemental clinical data: clinical details for the affected cases with mutations in novel candidate genes. (DOCX 35 kb

Additional file 2: Table S3. of Characterizing the morbid genome of ciliopathies

Clinical and genomic data for all cases in the study. (XLSX 83 kb

Additional file 8: Table S1. of Characterizing the morbid genome of ciliopathies

List of diagnostic criteria used to clinically classify each ciliopathy. (XLSX 10 kb

Additional file 1: Figure S1. of Characterizing the morbid genome of ciliopathies

Bar graph showing the percentage of the main features for each distinct ciliopathy syndrome. (PPTX 70 kb

Additional file 6: Table S5. of Characterizing the morbid genome of ciliopathies

Ciliopathy disease burden in the population for each pathogenic variant identified in known ciliopathy genes. (XLSX 19 kb

Additional file 5: Table S4. of Characterizing the morbid genome of ciliopathies

Identification of TXNDC15 interacting proteins using tandem affinity purification (TAP). The list of 224 unique proteins is significantly enriched in known or predicted ciliary proteins. (XLSX 30 kb

Additional file 7: Table S6. of Characterizing the morbid genome of ciliopathies

List of common variants with MAF of >0.01 that are listed as “disease-causing” variants in HGMD for known ciliopathy genes. (XLSX 12 kb