Segregation of a novel p.(Ser270Tyr) MAF mutation and p.(Tyr56∗) CRYGD variant in a family with dominantly inherited congenital cataracts.

A bilaterally blind woman, with a three generation family history of autosomal dominant congenital cataracts, variably associated with iris colobomata and microcornea, sought preconception genetic consultation. Whole-exome sequencing was performed in three affected family members, one unaffected first degree relative, and one spouse. The sequence variant c.168C>G; p.(Tyr56∗) in CRYGD, previously reported as pathogenic, and a novel mutation c.809C>A; p.(Ser270Tyr) in MAF, were identified in two affected family members; the grandmother, and half-brother of the proband. The proband inherited only the MAF mutation, whereas her clinically unaffected sister had the CRYGD change. In silico analysis supported a pathogenic role of p.(Ser270Tyr) in MAF, which was absent from publicly available whole-exome datasets, and 1161 Czech individuals. The frequency of CRYGD p.(Tyr56∗) in the ExAC dataset was higher than the estimated incidence of congenital cataract in the general population. Our study highlights that patients with genetically heterogeneous conditions may exhibit rare variants in more than one disease-associated gene, warranting caution with data interpretation, and supporting parallel screening of all genes known to harbour pathogenic mutations for a given phenotype. The pathogenicity of sequence variants previously reported as cataract-causing may require re-assessment in light of recently released datasets of human genomic variation.

Correction to: Segregation of a novel p.(Ser270Tyr) MAF mutation and p.(Tyr56*) CRYGD variant in a family with dominantly inherited congenital cataracts.

There was a spacing error in the initial online publication, and there were errors in the Acknowledgments section. The original article has been updated.

SNP array and phenotype correlation shows that FLI1 deletion per se is not responsible for thrombocytopenia development in Jacobsen syndrome.

Jacobsen syndrome (JBS) is a rare chromosomal disorder caused by terminal deletion of the long arm of chromosome 11. We report on four prenatally diagnosed patients with JBS with variable prenatal and postnatal phenotypes and 11q deletions of varying sizes. Precise characterization of the deleted region in three patients was performed by SNP arrays. The severity of both the prenatal and postnatal phenotypes did not correlate with the size of the haploinsufficient region. Despite the large difference in the deletion size (nearly 6 Mb), both of the live-born patients had similar phenotypes corresponding to JBS. However, one of the most prominent features of JBS, thrombocytopenia, was only present in the live-born boy. The girl, who had a significantly longer deletion spanning all four genes suspected of being causative of JBS-related thrombocytopenia (FLI1, ETS1, NFRKB, and JAM3), did not manifest a platelet phenotype. Therefore, our findings do not support the traditional view of deletion size correlation in JBS or the causative role of FLI1, ETS1, NFRKB, and JAM3 deletion per se for the development of disease-related thrombocytopenia.

ISPD gene homozygous deletion identified by SNP array confirms prenatal manifestation of Walker-Warburg syndrome.

Walker-Warburg syndrome (WWS) is a rare form of autosomal recessive, congenital muscular dystrophy that is associated with brain and eye anomalies. Several genes encoding proteins involved in abnormal α-dystroglycan glycosylation have been implicated in the aetiology of WWS, most recently the ISPD gene. Typical WWS brain anomalies, such as cobblestone lissencephaly, hydrocephalus and cerebellar malformations, can be prenatally detected through routine ultrasound examinations. Here, we report two karyotypically normal foetuses with multiple brain anomalies that corresponded to WWS symptoms. Using a SNP-array examination on the amniotic fluid DNA, a homozygous microdeletion was identified at 7p21.2p21.1 within the ISPD gene. Published data and our findings led us to the conclusion that a homozygous segmental intragenic deletion of the ISPD gene causes the most severe phenotype of Walker-Warburg syndrome. Our results also clearly supports the use of chromosomal microarray analysis as a first-line diagnostic test in patients with a foetus with one or more major structural abnormalities identified on ultrasonographic examination.