RESUMO
Despite the clinical significance of balanced chromosomal abnormalities (BCAs), their characterization has largely been restricted to cytogenetic resolution. We explored the landscape of BCAs at nucleotide resolution in 273 subjects with a spectrum of congenital anomalies. Whole-genome sequencing revised 93% of karyotypes and demonstrated complexity that was cryptic to karyotyping in 21% of BCAs, highlighting the limitations of conventional cytogenetic approaches. At least 33.9% of BCAs resulted in gene disruption that likely contributed to the developmental phenotype, 5.2% were associated with pathogenic genomic imbalances, and 7.3% disrupted topologically associated domains (TADs) encompassing known syndromic loci. Remarkably, BCA breakpoints in eight subjects altered a single TAD encompassing MEF2C, a known driver of 5q14.3 microdeletion syndrome, resulting in decreased MEF2C expression. We propose that sequence-level resolution dramatically improves prediction of clinical outcomes for balanced rearrangements and provides insight into new pathogenic mechanisms, such as altered regulation due to changes in chromosome topology.
Assuntos
Aberrações Cromossômicas , Anormalidades Congênitas/genética , Rearranjo Gênico , Marcadores Genéticos/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Feminino , Humanos , MasculinoRESUMO
OBJECTIVE: To investigate the association between fetal echogenic bowel (FEB) during the second trimester and perinatal outcome. METHODS: A retrospective chart review of FEB during the second trimester over 3 years. RESULTS: A total of 56 women were identified of 9067 screened (0.6%) women. Forty-seven agreed to genetic counseling (84%). Of those, 22 (39%) agreed to an amniocentesis. There were three cases of trisomy 21, one case of trisomy 18 and one case of fetal CMV infection. Twelve fetuses had an adverse outcome (21%), with only three of them having an echogenic bowel as the only finding. CONCLUSIONS: In our study, almost 80% of the fetuses had an uncomplicated perinatal outcome. FEB was present as the only finding in only 5% of the fetuses with an adverse outcome. A potential association with placental abnormalities and a low prevalence of viral infections was observed. These findings may be of use in counseling parents.
