One-month-old girl presenting with pseudohypoaldosteronism leading to the diagnosis of CDK13-related disorder: a case report and review of the literature

Background It is not uncommon that an infant with a disease of unknown etiology is presented to a physician. Facial dysmorphic features lead to a different diagnosis. It is a challenge to link the presentation to the newfound diagnosis. Case presentation A 37-day-old Yemenite Jewish girl was presented to our institution with a clinical picture of pseudohypoaldosteronism due to abnormal facial features and a psychomotor developmental delay. Further investigation led to the diagnosis of CDK13-related disorder. According to the literature, CDK13 has a key role in the cell cycle, but no interference with the aldosterone signaling pathway or electrolyte balance was described. No mutations in the previously described gene NR3C2 (cytogenetic location 4q31.23), encoding the mineralocorticoid receptor, were found. Although the clinical presentation corresponded to pseudohypoaldosteronism type 1, we could not genetically confirm this. Conclusions Probably pseudohypoaldosteronism was a coincidental finding in this girl with a CDK13 mutation, but because only limited information is known about CDK13-related disorders, further investigation could be more informative to clarify this presentation.

Karyotype variation in the albino rainbow trout (Oncorhynchus mykiss (Walbaum))

A Robertsonian polymorphism resulting in diploid chromosome number ranging from 59 to 61 and constant chromosome arm number (fundamental number = 104) was observed in the albino rainbow trout ( Oncorhynchus mykiss (Walbaum)) from the yellow color strain. In one individual, 90 mitotic chromosomes and 156 chromosome arms were counted, indicating the fish as a triploid. Morphology of the chromosomes, DAPI staining, and the cytogenetic location of 5S rDNA sequences showed sex-related chromosomal heteromorphism in the specimens. Additionally, length polymorphism of the X chromosome was detected in the studied individuals and two morphs of the X chromosome were described, XL and XS, according to the size of its short arm (p). The XS was observed in the female as well as male albino rainbow trout; however, among females, no XSXS genotype was found. After primed in situ labeling with 5S rDNA primers, the p-arms of both types of the X chromosome showed similar hybridization signals. On the other hand, fluorescence in situ hybridization with telomeric PNA (peptide nucleic acid) probe exhibited weak hybridization spots on the p-arm of the XS chromosome compared with the distinct hybridization spots observed on the XL p-arm. This could reflect a different telomere length on the p-arm of the XS and XL chromosomes. Partial translocation and deletion of the X chromosome p-arm are considered to be responsible for the p-arm length difference between the two morphological variants of X chromosome.

Molecular genetic analysis of the Drosophila melanogaster gene absent, small or homeotic discs1 (ash1).

The absent, small or homeotic discs1 gene (ash1) is one of the trithorax set of genes. Recessive loss of function mutations in ash1 cause homeotic transformations of imaginal disc derived tissue which resemble phenotypes caused by partial loss or gain of function mutations in genes of the Antennapedia Complex and bithorax Complex. F2 screens were used to isolate P element insertion alleles and EMS-induced alleles of ash1, including one temperature-sensitive allele, and an F1 screen was used to isolate gamma-ray-induced alleles. Analysis of ash1 mutant flies that survive until the adult stage indicates that not only imaginal disc- and histoblast-derived tissues are affected but also that oogenesis requires ash1 function. Mutations in the gene brahma (brm) which also is one of the trithorax set of genes interact with mutations in ash1 such that non-lethal ash1 +/+ brm double heterozygotes have a high penetrance of homeotic transformations in specific imaginal disc- and histoblast-derived tissues. The cytogenetic location of ash1 was determined to be 76B6-11 by the breakpoint of a translocation recovered in the F1 screen. The gene Shal, which is located cytogenetically nearby ash1, was used to initiate an 84-kb genomic walk within which the ash1 gene was identified. The ash1 gene encodes a 7.5-kb transcript that is expressed throughout development but is present at higher levels during the embryonic and pupal stages than during the larval stages. During the larval stages the transcript accumulates primarily in imaginal discs. During oogenesis the transcript accumulates in the nurse cells of developing egg chambers.

TRANSPOSABLE ELEMENTS IN MENDELIAN POPULATIONS. II. DISTRIBUTION OF THREE COPIA-LIKE ELEMENTS IN A NATURAL POPULATION OF DROSOPHILA MELANOGASTER

ABSTRACT Twenty X chromosomes isolated from a natural population of Drosophila melanogaster were surveyed using in situ hybridization to determine the number and cytogenetic location of three families of transposable elements: copia, 412 and 297. We found no sites of insertions in high frequency; in fact, frequencies of specific sites for all three elements were so low that each insertion could be interpreted as being unique. This suggests that rates of transposition and deletion for these elements are very high. Our data also show a higher than expected rate of the co-occurrence of different elements at the same site on the same chromosome.