Investigation of the 22q11.2 candidate region in patients with midline facial defects with hypertelorism

DNA methylation dysregulation patterns in the 1p36 region instability

In the monosomy 1p36 deletion syndrome, the role of DNA methylation in the genomic stability of the 1p36 region remains elusive. We hypothesize that changes in the methylation pattern at the 1p36 breakpoint hotspot region influenced the chromosomal breakage leading to terminal deletions. From the monosomy 1p36 material collection, four cases with 4.0 to 5.5 Mb terminal deletions and their parents were investigated. DNA samples were assessed by targeted bisulfite sequencing (NimbleGen SeqCap Epi) to examine DNA methylation status in the 1p36 hotspot region at single-base resolution as compared to the chromosomal hotspot regions, 9p22, 18q21.1, and 22q11.2. Additionally, in in silico assessment, the mean GC content of various classes of repeats in the genome and especially in the breakpoint regions was evaluated. A complex landscape of DNA methylation in the 1p36 breakpoint hotspot region was found. Changes in DNA methylation level in the vicinity of the breakpoint in the child's DNA when compared to parents' and control DNA were observed, with a shift from 15.1 to 70.8% spanning the breakpoint region. In the main classes of evaluated repeats, higher mean GC contents in the 1p36 breakpoint region (47.06%), 22q11.2 (48.47%), and 18q21.1 (44.21%) were found, compared to the rest of the genome (40.78%). The 9p22 region showed a lower GC content (39.42%) compared to the rest of the genome. Both dysregulation of DNA methylation and high GC content were found to be specific for the 1p36 breakpoint hotspot region suggesting that methylation abnormalities could contribute to aberrations at 1p36.

Two novel mutations within FREM1 gene in patients with bifid nose

BACKGROUND

Bifid nose is a rare congenital deformity and the etiology is unknown. The purpose of this study was to report genetic variation in family of patients with bifid nose.

METHODS

Twenty-three consecutive patients who were diagnosed with mild bifid nose were operated with z-plasty from 2009 to 2021. Three underage patients (a pair of twins and a girl) from two family lines, who came to our hospital for surgical treatment, were enrolled. Whole exome sequencing and Sanger sequencing were conducted. Z-shaped flaps were created and the cartilago alaris major were re-stitched. Photographs and CT scan before and after surgery were obtained. Clinical outcomes, complications and patients' satisfaction were evaluated and analyzed. The follow-up time ranges from 2 to 3 years (2.4 ± 1.2 years).

RESULTS

Most patients were satisfied with the outcome (96.2%). The nasal deformities were corrected successfully with z-plasty technique in one-stage. FREM1 c.870_876del and c.2 T > C were detected with Whole exome sequencing, which have not been reported before. The results of Sanger sequencing were consistent with those of Whole exome sequencing.

CONCLUSIONS

The newly detected mutations of FREM1 have a certain heritability, and are helpful to make an accurate diagnosis and provide a better understanding of bifid nose mechanism. Z-plasty technique can be an effective technical approach for correcting mild bifid nose deformity.

Maternally inherited partial monosomy 9p (pter → p24.1) and partial trisomy 20p (pter → p12.1) characterized by microarray comparative genomic hybridization

We report on a 17-year-old patient with midline defects, ocular hypertelorism, neuropsychomotor development delay, neonatal macrosomy, and dental anomalies. DNA copy number investigations using a Whole Genome TilePath array consisting, of 30K BAC/PAC clones showed a 6.36 Mb deletion in the 9p24.1-p24.3 region and a 14.83 Mb duplication in the 20p12.1-p13 region, which derived from a maternal balanced t(9;20)(p24.1;p12.1) as shown by FISH studies. Monosomy 9p is a well-delineated chromosomal syndrome with characteristic clinical features, while chromosome 20p duplication is a rare genetic condition. Only a handful of cases of monosomy 9/trisomy 20 have been previously described. In this report, we compare the phenotype of our patient with those already reported in the literature, and discuss the role of DMRT, DOCK8, FOXD4, VLDLR, RSPO4, AVP, RASSF2, PROKR2, BMP2, MKKS, and JAG1, all genes mapping to the deleted and duplicated regions.