P-740 Monogenic and digenic variants in male PLCZ1, ACTL7A and ACTL9 genes cause fertilization failure after ICSI

Abstract Study question What is the frequency of PLCZ1, ACTL7A and ACTL9 variants in male patients suffering from fertilization failure (FF) after ICSI? Summary answer Male with FF ICSI exhibit PLCZ1 (27,3%), (13,6%) (4,5%). Some present combined ACTL7A/ACTL9 variants. known already has been often attributed to phospholipase C zeta (PLCζ) deficiency, consequently insufficient calcium release, necessary for fertilization. genetic have detected one-third males FF. Recently, actin-like 7A (ACTL7A) 9 (ACTL9) were also identified, but larger cohort studies are lacking. alter acrosome structure, resulting reduced abnormally localized PLCζ. Assisted oocyte activation (AOA), by ionophore, restores variants, could benefit defects. This study aimed expand spectrum design, size, duration A prospective was conducted June 2020 December 2022 including 22 (P1-P22) ICSI. Patients only recruited when they had a mean rate ≤33,33% at least 1 cycle. All donated saliva sample screening genes sperm mouse activating test (MOAT). couples offered an AOA treatment. Participants/materials, setting, methods Genetic performed via next-generation sequencing. Identified classified employing Varsome confirmed bidirectional Sanger which uncertain significance (VUS), likely pathogenic or found underwent additional diagnostic tests, such as releasing pattern (MOCA) vitro matured (IVM) human (HOCA) oocytes, immunostaining PLCζ ACTL7A, analysis morphology transmission electron microscopy (TEM). Main results role chance revealed heterozygous novel variant p.Ile379Thr P10 previously published p.His233Leu three (P9, P19 P20). In addition, two homozygous detected, p.Ser364GlnfsTer9 P1 p.Gly214Ser P22. Interestingly, digenic observed P6 (PLCZ1 p.Ile74Thr p.Tyr183His) P8 p.Arg271Pro). identified showed high (>70%) MOAT, except P22 <25%, indicating more detrimental sperm-related deficiency. While MOCA deficient release (and not P6, P8, P9 P10), HOCA absence oscillations all analyzed (P1, P6. Immunostaining experiments no signal decreased patient sperm. Moreover, TEM detachment nuclear membrane. Overall, increased (from 7,23% 53,04%) pregnancy 7,14% 46,15%) Specifically, monogenic (P9 P19) (P1) well (P6 P8) achieved live birth AOA. Limitations, reasons caution undergone tests yet, thus functional data on still ongoing. recruitment this continuing. carried exonic flanking intronic regions, might missed other regions. Wider implications findings The MOAT/MOCA cannot detect some subtle deficiencies. represents sensitive requires oocytes. Therefore, ACLTL9 be faster cost-efficient Furthermore, treatment very efficient these patients. Trial registration number NA