Background and Aims: This is the first national population-based report about prenatal diagnosis for families with a history of facioscapulohumeral muscular dystrophy (FSHD), a complex hereditary disease. The incomplete disease penetrance and the phenotypic heterogeneity observed in carriers of D4Z4 alleles of reduced size, the FSHD molecular hallmark, make the estimate of genetic risk problematic. Methods:We considered all requests of preconception counseling and prenatal diagnosis received between January 2008 and December 2020 by the genetic counseling service associated with the Italian National Registry for FSHD (INRF).A multidisciplinary team managed the clinical and molecular data of each family.Results: Between 2008 and 2020, 60 couples required preconception counseling (PC) for FSHD. In 52 couples was observed at least one partner carried a D4Z4 reduced allele (DRA). Out of these 52 couples, 47 had a follow-up visit routine yearly. Out of these 47, 26 (55.3%) couples had children: eight asked for prenatal diagnosis (PND), two had assisted reproduction by heterologous in vitro fertilization (IVF), and 16 did not require further assistance. Regarding PND, 50 prenatal analyses were performed for 36 couples. The test resulted positive in 27 pregnancies, 12 (44.4%) were terminated, and 15 (55.6%) were carried to term. Conclusion:The different choices made by the couples show the importance of an integrated approach to support genetic counseling for FSHD. These results remark the relevance of the clinical and molecular investigation of the extended family, preferably before conception.

Background Titin truncating variants (TTNtv) have been associated with several forms of myopathies and/or cardiomyopathies. In homozygosity or in compound heterozygosity they cause a wide spectrum of recessive phenotypes with a congenital or childhood onset. Most recessive phenotypes showing a congenital or childhood onset have been described in subjects carrying biallelic TTNtv in specific exons. However, TTN is not yet included in many NGS panels for congenital musculoskeletal anomalies and dysmorphisms, and karyotype or chromosomal microarray analyses are often the only tests performed when prenatal anomalies are identified. Thereby, many cases caused by TTN defects might be missed in the diagnostic evaluations. In this study, we aimed to dissect the most severe end of the titinopathies spectrum. Methods We analyzed an international cohort of 93 published and 10 unpublished cases carrying biallelic TTNtv. Results We identified recurrent clinical features in antenatal and congenital recessive titinopathies, including fetal akinesia, arthrogryposis, facial dysmorphisms, joint, bone, and heart anomalies resembling complex, syndromic phenotypes. Conclusion We suggest TTN to be carefully evaluated in any diagnostic process involving patients with the mentioned signs. This step will be essential to improve diagnostic performance, expand our knowledge, and optimize prenatal genetic counseling.

BackgroundTitin truncating variants (TTNtvs) have been associated with several forms of myopathies and/or cardiomyopathies. In homozygosity or in compound heterozygosity, they cause a wide spectrum of recessive phenotypes with a congenital or childhood onset. Most recessive phenotypes showing a congenital or childhood onset have been described in subjects carrying biallelic TTNtv in specific exons. Often karyotype or chromosomal microarray analyses are the only tests performed when prenatal anomalies are identified. Thereby, many cases caused byTTNdefects might be missed in the diagnostic evaluations. In this study, we aimed to dissect the most severe end of the titinopathies spectrum.MethodsWe performed a retrospective study analysing an international cohort of 93 published and 10 unpublished cases carrying biallelic TTNtv.ResultsWe identified recurrent clinical features showing a significant correlation with the genotype, including fetal akinesia (up to 62%), arthrogryposis (up to 85%), facial dysmorphisms (up to 73%), joint (up to 17%), bone (up to 22%) and heart anomalies (up to 27%) resembling complex, syndromic phenotypes.ConclusionWe suggestTTNto be carefully evaluated in any diagnostic process involving patients with these prenatal signs. This step will be essential to improve diagnostic performance, expand our knowledge and optimise prenatal genetic counselling.

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