Single-nucleotide polymorphism array-based characterization of ring chromosome 18.

Objective: To study genotype-phenotype correlation of ring chromosome 18 [r(18)] in 9 patients with 46,XN karyotype.

Study Design: In 9 patients with a de novo 46,XN,r(18) karyotype (7 females, 2 males), we performed high-resolution single-nucleotide polymorphism array analysis (Illumina Human Omni1-QuadV1 array in 6 patients, Affymetrix 6.0 array in 3 patients), investigation of parental origin, and genotype-phenotype correlation.

The mitochondrial solute carrier SLC25A5 at Xq24 is a novel candidate gene for non-syndromic intellectual disability.

Loss-of-function mutations in several different neuronal pathways have been related to intellectual disability (ID). Such mutations often are found on the X chromosome in males since they result in functional null alleles. So far, microdeletions at Xq24 reported in males always have been associated with a syndromic form of ID due to the loss of UBE2A.

Disruption of EXOC6B in a patient with developmental delay, epilepsy, and a de novo balanced t(2;8) translocation.

Most balanced chromosomal aberrations are not associated with a clinical phenotype, however, in some patients they may disrupt gene structure. With the development of various next-generation sequencing techniques, fast and specific analyses of the breakpoint regions of chromosomal rearrangements are possible. Here, we report on a 19-year-old woman with a de novo balanced translocation t(2;8)(p13.

Novel mutation in potassium channel related gene KCTD7 and progressive myoclonic epilepsy.

Progressive myoclonic epilepsy (PME) is a heterogeneous group of epilepsies characterized by myoclonus, seizures and progressive neurological symptoms. The index patient was a 6-year old boy showing early-onset therapy resistant PME and severe developmental delay. Genome-wide linkage analysis identified several candidate regions.

Microdeletion 19p13.2 in an almost 5-year-old boy.

Deletions of the short arm of chromosome 19 are rarely found by conventional cytogenetic techniques. This region has a high gene density and this is likely the reason why deletions in this region are associated with a severe phenotype. Since the implementation of modern high-resolution SNP- and CGH-array techniques more cases have been reported.

Phenotypic variability of a deletion and duplication 6q16.1 → q21 due to a paternal balanced ins(7;6)(p15;q16.1q21).

Constitutional insertional translocations are rare findings in clinical cytogenetics. Here, we report on the unbalanced segregation of a balanced paternal insertional translocation ins(7;6)(p15;q16.1q21) to three children.

Parental origin and mechanism of formation of a 46,X,der(X)(pter-->q21.1::p11.4-->pter)/45,X karyotype in a woman with mild Turner syndrome.

Objective: To describe the parental origin and the mechanism of formation of a 46,X,der(X)(pter-->q21.1::p11.4-->pter)[23]/45,X[8] karyotype in a patient with mild Turner syndrome.