Apparent Homozygosity for a gr/gr AZFc Deletion in A 47,XYY Man with Oligozoospermia and Secondary Infertility.

Background: Approximately 1 in 1000 men have a 47,XYY karyotype. Previous publications have presented cases of infertile XYY men and have suggested that the additional Y chromosome may cause disrupted meiosis leading to sperm apoptosis. The purpose of the current study was to determine whether XYY men are over-represented in infertility cohorts. Methods: In this paper, an ongoing infertility cohort was evaluated for Y chromosome microdeletions using the MLPA technique and the data from the first 2000 referrals were recorded. Moreover, the MLPA technique detected 47,XYY karyotypes. Results: Four XYY individuals were identified within the cohort. One of the four XYY men was shown to have an apparent gr/gr partial AZFc deletion on both Y chromosomes while Sertoli cell only syndrome was detected in another case. The other two cases (out of 2000) might, therefore, represent an incidental finding. Conclusion: The gr/gr deletion is not detectable by the multiplex PCR method; therefore, there might be additional explanations for the fertility problems of infertile XYY men reported in previously published articles. It seems that among other cases, their XYY karyotype may be coincidental, rather than causative of their fertility issues.

SHOX Whole Gene Duplications Are Overrepresented in SHOX Haploinsufficiency Phenotype Cohorts.

Transcription of SHOX is dependent upon the interaction of the gene with a complex array of flanking regulatory elements. Duplications that contain flanking regulatory elements but not the SHOX gene have been reported in individuals with SHOX haploinsufficiency syndromes, suggesting that alterations to the physical organisation or genomic architecture may affect SHOX transcription. Individuals with tall stature and an additional X or Y chromosome have an extra copy of both the SHOX gene and the entire SHOX regulatory region, so all three copies of SHOX can be expressed fully. However, for a duplication of the SHOX gene that does not include all of the flanking regulatory elements, the potential effect on SHOX expression is difficult to predict. We present nine unpublished individuals with a SHOX whole gene duplication in whom the duplication contains variable amounts of the SHOX regulatory region, and we review 29 similar cases from the literature where phenotypic data were clearly stated. While tall stature was present in a proportion of these cases, we present evidence that SHOX whole gene duplications can also result in a phenotype more typically associated with SHOX haploinsufficiency and are significantly overrepresented in Leri-Weill dyschondrosteosis and idiopathic short stature probands compared to population controls. Although similar-looking duplications do not always produce a consistent phenotype, there may be potential genotype-phenotype correlations regarding the duplication size, regulatory element content, and the breakpoint proximity to the SHOX gene. Although ClinGen does not currently consider SHOX whole gene duplications to be clinically significant, the ClinGen triplosensitivity score does not take into account the context of the duplication, and more is now known about SHOX duplications and the role of flanking elements in SHOX regulation. The evidence presented here suggests that these duplications should not be discounted without considering the extent of the duplication and the patient phenotype, and should be included in diagnostic laboratory reports as variants of uncertain significance. Given the uncertain pathogenicity of these duplications, any reports should encourage the exclusion of all other causes of short stature where possible.

Screening of a large Rubinstein-Taybi cohort identified many novel variants and emphasizes the importance of the CREBBP histone acetyltransferase domain.

Pathogenic variants within the CREBBP and EP300 genes account for the majority of individuals with Rubinstein-Taybi syndrome (RSTS). Data are presented from a large cohort of 395 individuals referred for diagnostic testing of CREBBP, and of the 19 CREBBP missense variants classified as likely pathogenic in this study, 17 were within the histone acetyltransferase (HAT) domain, providing evidence that this domain is critical to the normal function of the CREBBP protein (CBP). The data presented here, combined with other published results, suggest that the presence of a missense variant within the CBP HAT domain can be considered as moderate evidence of pathogenicity in the context of official variant interpretation guidelines. Within our study cohort, 129 had a pathogenic or likely pathogenic CREBBP variant and 5 had a variant of uncertain significance (VUS) which warranted familial studies. 147 of the remaining probands were also screened for EP300 and a further 16 pathogenic or likely pathogenic variants were identified, plus one VUS. Therefore, this analysis has provided a molecular diagnosis in at least 145 individuals with RSTS (37%) and identified a wide range of variants (n = 133) of which 103 were novel.

Screening of a large PAX6 cohort identified many novel variants and emphasises the importance of the paired and homeobox domains.

Pathogenic variants within PAX6 are most often associated with aniridia, but have been linked with other phenotypes such as nystagmus, cataracts and foveal hypoplasia. Data are presented from a large cohort of 434 probands referred for PAX6 diagnostic testing. This analysis identified a wide range of pathogenic variants (n = 145) in 254 probands (including 61 novel variants). Excluding missense variants predicted to affect splicing, all 29 of the remaining missense variants were located within the paired (n = 27) or homeobox (n = 2) domains of the PAX6 protein, providing further evidence that these domains are critical to normal PAX6 function. Genotype-phenotype evidence suggests that while aniridia is associated with most variant types, a much broader clinical spectrum is seen in patients harbouring a missense variant, or a frameshift or run-on variant that results in an elongated or extended PAX6 protein.

Genetic analysis of chromosome 11p13 and the PAX6 gene in a series of 125 cases referred with aniridia.

A series of 125 patients referred primarily with aniridia classified as either sporadic (74), familial (24), or in association with WAGR syndrome (14) or other malformations (13) was analysed for mutations, initially by karyotyping and targeted FISH analysis of chromosome 11p13. These methods identified mutations in a significant proportion of patients, 34/125 (27%). Two cases had chromosome rearrangements involving 11p13, 16 cases had visible deletions, and 16 cases had cryptic deletions identified by FISH. The frequency of cryptic deletions in familial aniridia was 27% and in sporadic isolated aniridia was 22%. Of the 14 cases referred with WAGR syndrome, 10 (71%) had chromosomal deletions, 2 cryptic and 8 visible. Of the 13 cases with aniridia and other malformations, 5 (38%) had a chromosomal rearrangement or deletion. In 37 cases with no karyotypic or cryptic chromosome abnormality, sequence analysis of the PAX6 gene was performed. Mutations were identified in 33 cases; 22 with sporadic aniridia, 10 with familial aniridia and 1 with aniridia and other non-WAGR syndrome associated anomalies. Overall, 67 of 71 cases (94%) undergoing full mutation analysis had a mutation in the PAX6 genomic region.

Ocular findings in Gillespie-like syndrome: association with a new PAX6 mutation.

BACKGROUND: Gillespie syndrome is a rare variant form of aniridia, characterized by mental retardation, nonprogressive cerebellar ataxia, and iris hypoplasia. Unlike the more common dominant and sporadic forms of aniridia, there have been no associated PAX6 mutations or Wilms' tumor reported in Gillespie syndrome patients. Ocular findings in 21 cases published since Gillespie's initial description in 1965 include iris and foveal hypoplasia, nystagmus, and small optic discs with pigmentary retinopathy. CASE REPORT: We herein report a case of atypical Gillespie syndrome associated with bilateral ptosis, exotropia, corectopia, iris hypoplasia, anterior capsular lens opacities, foveal hypoplasia, retinal vascular tortuosity, and retinal hypopigmentation. Neurologic evaluation revealed a mild hand tremor and learning disability, but no ataxia or cerebellar abnormalities on neuroimaging. Sequencing studies revealed a substitution in intron 2 of the PAX6 gene (IVS2 + 2T > A). To our knowledge, this is the first mutation of PAX6 gene reported in association with a Gillespie-like syndrome.