Association of Meier-Gorlin and microcephalic osteodysplastic primordial dwarfism type II clinical features in an individual with CDK5RAP2 primary microcephaly.

Autosomal recessive primary microcephaly type 3 (MCPH3) caused by pathogenic variations in CDK5RAP2, is characterized by sensorineural hearing loss, abnormality of skin pigmentation, ocular defects and severe microcephaly associated with neurodevelopmental delay. In this study, we expand the phenotype of MCPH3 as we describe a 10-year-old girl with a biallelic exonic frameshift variant in CDK5RAP2 displaying previously unreported features usually associated with Meier-Gorlin and microcephalic osteodysplastic primordial dwarfism type II (MOPDII). We further describe the clinical phenotype of this form of centrosomal-based primary microcephaly and emphasize the importance of skeletal defect screening in affected individuals.

Rapid exome sequencing in critically ill infants: implementation in routine care from French regional hospital's perspective.

This monocentric study included fifteen children under a year old in intensive care with suspected monogenic conditions for rapid trio exome sequencing (rES) between April 2019 and April 2021. The primary outcome was the time from blood sampling to rapid exome sequencing report to parents. All results were available within 16 days and were reported to parents in or under 16 days in 13 of the 15 individuals (86%). Six individuals (40%) received a diagnosis with rES, two had a genetic condition not diagnosed by rES. Eight individuals had their care impacted by their rES results, four were discharged or died before the results. This small-scale study shows that rES can be implemented in a regional University hospital with rapid impactful diagnosis to improve care in critically ill infants.

Refining the clinical phenotype associated with missense variants in exons 38 and 39 of KMT2D.

Loss-of-function variants in KMT2D are responsible for Kabuki syndrome type 1 (KS1). In the last 5 years, missense variants in exon 38 or 39 in KMT2D have been found in patients exhibiting a new phenotype with multiple malformations and absence of intellectual disability, distinct from KS1. To date, only 16 cases have been reported with classic features of hearing loss, abnormality of the ear, lacrimal duct defects, branchial sinus/neck pits, choanal atresia (CA), athelia, hypo(para)thyroidism, growth delay, and dental anomalies. We report here two families and one unpublished variant, refining the clinical and molecular knowledge on this new entity. Family 1 presented with apparently isolated autosomal dominant choanal atresia, in eight members across three generations. Exome sequencing (ES) in the proband and one cousin revealed a p.Glu3569Gly variant in exon 38 of KMT2D, segregating with choanal atresia in the family. Clinical reevaluation evidenced thyroid dysfunction, mild hearing anomalies, and hypoplastic nipple in some patients. Family 2 presented with nasolacrimal duct obstruction, hearing loss, mild facial features, unilateral axial polydactyly, and unilateral toe V-VI syndactyly. ES revealed a de novo already reported p.Arg3582Gln variant in exon 38 of KMT2D. Considering these results and the existing literature, we suspect that missense variants in exon 38 of KMT2D are responsible for phenotypes that are even milder (isolated CA) and broader (polydactyly) than what has been previously described.