Craniofacial Microsomia, Associated Congenital Anomalies, and Risk Factors in 63 Cases from the Alberta Congenital Anomalies Surveillance System

Chromatin assembly factor subunit CHAF1A as a monogenic cause for oculo-auriculo-vertebral spectrum

Oculo-auriculo-vertebral spectrum (OAVS) is characterized by abnormal development of the 1st and 2nd branchial arches. Despite arguments against a monogenic condition, a few genes have been involved in a minority of cases. We now report heterozygous, presumably loss-of function variants in the CHAF1A gene in 8 individuals, including 3 members of the same family. Four cases fulfill stringent diagnostic criteria for OAVS, including asymmetric ear dysplasia, preauricular tags, mandibular asymmetry +/- vertebral malformations. Two patients also presented with kidney malformations. CHAF1A encodes a subunit of CAF-1 (chromatin assembly factor-1), a heterotrimeric protein complex responsible for the deposition of newly synthesized histones H3-H4 onto the newly synthetized DNA strand during replication. The identification of loss-of-unction variants in CHAF1A is consistent with the hypothesis of early developmental genes dysregulation driving OAVS and other associations recently lumped under the acronym Recurrent Constellations of Embryonic Malformations (RCEM).

Identification of a DNA methylation episignature for recurrent constellations of embryonic malformations

The term "recurrent constellations of embryonic malformations" (RCEM) is used to describe a number of multiple malformation associations that affect three or more body structures. The causes of these disorders are currently unknown, and no diagnostic marker has been identified. Consequently, providing a definitive diagnosis in suspected individuals is challenging. In this study, genome-wide DNA methylation analysis was conducted on DNA samples obtained from the peripheral blood of 53 individuals with RCEM characterized by clinical features recognized as VACTERL and/or oculoauriculovertebral spectrum association. We identified a common DNA methylation episignature in 40 out of the 53 individuals. Subsequently, a sensitive and specific binary classifier was developed based on the DNA methylation episignature. This classifier can facilitate the use of RCEM episignature as a diagnostic biomarker in a clinical setting. The study also investigated the functional correlation of RCEM DNA methylation relative to other genetic disorders with known episignatures, highlighting the common genomic regulatory pathways involved in the pathophysiology of RCEM.

Prenatal findings in 11 cases with craniofacial microsomia using the Alberta Congenital Anomalies Surveillance System, 1997-2019

Craniofacial microsomia (CFM) primarily includes specific head and neck anomalies that co-occur more frequently than expected. The anomalies are usually asymmetric and affect craniofacial features; however, there are frequently additional anomalies of variable severity. Published prenatal findings for CFM are limited. This study contributes 11 cases with CFM and their anomalies identified prenatally. Cases born between January 1, 1997 and December 31, 2019 with CFM were abstracted from the Alberta Congenital Anomalies Surveillance System, which is a population-based program ascertaining congenital anomalies for livebirths, stillbirths, and termination of pregnancies for fetal anomalies. There were 11 cases ascertained with prenatal findings including facial anomalies: one each with left cleft lip, right microtia, and bilateral microphthalmia. Two cases had vertebral anomalies. In addition, anomalies of the kidneys, brain, heart, and radial ray were identified. Six (55%) had a single umbilical artery, five (45%) were small for gestational age, and three (27%) were from a twin pregnancy that were discordant for anomalies. Four (36%) overlapped another proposed recurrent constellations of embryonic malformation condition. This study describes prenatal findings for 11 cases with CFM. Comparable to prior published cases, there were recurring anomalies on prenatal imaging, including anomalies of the brain, eye, heart, kidneys, and radial ray, which may aid in the prenatal diagnosis of CFM.

Risk factors and characteristics of the birth of patients with craniofacial microsomia, a case-control study

BACKGROUND

Craniofacial microsomia (CM) is characterized by changes in the first and second branchial arches. It is a clinical condition whose etiology is still uncertain, but studies have shown that genetic, nutritional, and environmental factors can result in disorders of blastogenesis of the branchial arches. This study evaluates gestational aspects, focusing on possible risk factors associated with CM.

METHODS

This is a case-control study conducted with patients monitored at a medical genetics service and compared to a control group of patients without evidence of malformations, born in a mother and child hospital, both located in Porto Alegre, Southern Brazil. Mothers' data were obtained using questionnaires and by reviewing medical records. The sample consisted of 43 patients with CM (cases) and 129 patients without evidence of malformations (controls), paired by sex, totaling three controls for each case. Data analysis was performed using the two-tailed Fisher's exact test, Pearson's chi-square test, and the t-test.

RESULTS

We identified several factors associated with the development of CM, including the use of abortion methods by the mothers of these babies (p = .001), maternal diabetes (p = .009), advanced maternal age (p = .035), and a history of vaginal bleeding (p < .001). Furthermore, these patients exhibited a tendency to be born prematurely (p = .027), with low birth weight (p = .007), and lower Apgar scores (p = .003) when compared to healthy infants. Using a multivariate model, the use of abortion methods (p = .003) and vaginal bleeding (p = .032) remained independently associated with craniofacial microsomia.

CONCLUSIONS

We have identified several risk factors for the development of CM, including a propensity for premature birth, low birth weight, and respiratory difficulties. Additionally, women of advanced maternal age and/or those who used abortion methods and/or have diabetes have a higher risk of giving birth to a baby with CM. This information can be valuable in clinical practice, especially for the prevention of future cases.