Variants in the WDR44 WD40-repeat domain cause a spectrum of ciliopathy by impairing ciliogenesis initiation.

WDR44 prevents ciliogenesis initiation by regulating RAB11-dependent vesicle trafficking. Here, we describe male patients with missense and nonsense variants within the WD40 repeats (WDR) of WDR44, an X-linked gene product, who display ciliopathy-related developmental phenotypes that we can model in zebrafish. The patient phenotypic spectrum includes developmental delay/intellectual disability, hypotonia, distinct craniofacial features and variable presence of brain, renal, cardiac and musculoskeletal abnormalities. We demonstrate that WDR44 variants associated with more severe disease impair ciliogenesis initiation and ciliary signaling. Because WDR44 negatively regulates ciliogenesis, it was surprising that pathogenic missense variants showed reduced abundance, which we link to misfolding of WDR autonomous repeats and degradation by the proteasome. We discover that disease severity correlates with increased RAB11 binding, which we propose drives ciliogenesis initiation dysregulation. Finally, we discover interdomain interactions between the WDR and NH2-terminal region that contains the RAB11 binding domain (RBD) and show patient variants disrupt this association. This study provides new insights into WDR44 WDR structure and characterizes a new syndrome that could result from impaired ciliogenesis.

[Preimplantation genetic testing].

Preimplantation genetic testing (PGT) for known familial monogenetic disease (PGT-M) or structural chromosomal rearrangements (PGT-SR) has evolved into a well-established alternative to prenatal diagnosis. PGT significantly reduces the risk of a pregnancy with an affected foetus. Screening for aneuploidy (PGT-A) used as an add-on to standard IVF treatment of infertile couples is widely used internationally, although its benefit is highly debated. PGT combines genetic counselling and testing with assisted reproductive technology including ovarian stimulation, egg retrieval, and embryo biopsy, as discussed in this review.

[Genetic screening of prospective parents].

Risk of genetic diseases with autosomal recessive or X-linked inheritance can be unknown to prospective parents until an affected child is born. New technology has enabled carrier screening for hundreds of genetic diseases (expanded carrier screening, ECS). I Denmark, each year estimated 100-180 children are born affected with a serious condition which could have been detected with ECS of the parents. This review describes the considerations and perspectives of a systematic genetic screening programme for prospective parents in the Danish healthcare system.

[The genetic background for the eye malformations anophthalmia and microphthalmia]. / Den genetiske baggrund for øjenmisdannelserne mikroftalmi og anoftalmi.

Anophthalmia and microphthalmia (AO/MO) are rare congenital eye malformations, in which the eyeball is apparently absent or smaller than normal, which causes various degrees of visual impairment. Over 200 different AO/MO-related syndromes have been described, but the genetic background is unknown in many cases. The aim of this article is to give an overview of AO/MO, focusing on the genetic background. It is illustrated that the future identification of new AO/MO related genes will benefit in the genetic counseling of AO/MO patients, and in the understanding of eye development and congenital eye malformations.