Exploring the factors affecting classification and reporting of uncertain prenatal microarray findings, using a "virtual fetus" model-a pilot study.

OBJECTIVE: Significant discrepancy exists between laboratories in classification and reporting of copy number variants (CNVs). Studies exploring factors affecting prenatal CNV management are rare. Our "virtual fetus" pilot study examines these factors. METHOD: Ten prenatally diagnosed CNVs of uncertain significance (VUS) > 1Mb, encompassing OMIM-morbid genes, inherited from healthy parents, were classified by 15 MD geneticists from laboratory, prenatal, and preimplantation genetic testing (PGT) units. Geneticists addressed factors affecting classification, obligation to report, and recommendation for invasive testing or PGT. RESULTS: CNVs were classified likely benign (10.7%), VUS (74.7%), likely pathogenic (8.7%), or pathogenic (6.0%). Classification discrepancy was higher for losses versus gains. Classifying pathogenic/likely pathogenic was more common for losses (adjusted odds ratio [aOR] 10.9, 95% CI 1.55-76.9), and geneticists specializing in gynecology (aOR 4.9, 95% CI 1.03-23.3). 84.0% of respondents would report CNVs, depending on classification and family phenotype. Invasive testing in pregnancies was recommended for 29.3% of CNVs, depending on the classification and geneticist's specialization. PGT was recommended for 32.4%, depending on classification, experience years, and family's phenotype (38.0% for patients undergoing in vitro fertilization irrespectively, 26.7% otherwise). CONCLUSION: Factors affecting CNV classification/reporting are mainly dosage, family phenotype, geneticist specialization and experience. Understanding factors from our pilot study may facilitate developing an algorithm for clinical consensus and optimal management.

A novel RYR1 pathogenic variant - Common among Libyan Jews and associated with a broad phenotypic spectrum.

Mutated skeletal muscle ryanodine receptor-1 (RYR1) gene is associated with a spectrum of autosomal dominant and recessive RyR1-related disorders with a wide phenotype. This report describes a variable phenotype associated with a previously unreported RYR1 frameshift pathogenic variant, (NM_000540.2) c.12815_12825del; p.Ala4272Glyfs*307, common in Libyan Jews. Clinical and genetic features of 14 carriers from 8 unrelated families were collected. There were 12 heterozygotes and 2 compound heterozygotes. Six heterozygotes (median age 49.8) were asymptomatic, and six (median age 24.5) presented with myopathy (n = 3) or severe arthrogryposis-like features, severe scoliosis, pes planus, post-anesthesia malignant hyperthermia, or cystic hygroma (in a fetus) (n = 1 each). None had an abnormal echocardiogram study or elevated creatine phosphokinase (CPK) levels. One bi-allelic carrier had a severe skeletal phenotype and myopathy; the other was a fetus with a cystic hygroma. Assessment of variant frequency in 447 Libyan Jews who underwent exome testing for unrelated reason yielded a prevalence of 1:55. The RYR1 p.Ala4272Glyfs*307 variant is common in Libyan Jews. It is associated with a broad phenotypic spectrum, with possible presentation among heterozygotes. Further genotype-phenotype studies are essential to delineate the clinical significance of the variant in mono- and bi-allelic carriers.