Monogenic Versus Multifactorial Inheritance in the Development of Isolated Cleft Palate: A Whole Genome Sequencing Study

How are people with orofacial clefts attended in northwest region of São Paulo state, Brazil?

Characterization of specific birth defects is essential for conducting scientific investigations, care and therapeutic strategies. This article describes demographic, clinical and genetic aspects, risk factors and access to treatment of Brazilian patients with orofacial clefts registered in a specialized collaborative center of the Brazilian Database on Craniofacial Anomalies (BDCA). We interviewed 70 individuals with typical orofacial clefts using a standard instrument from the database and subjected them to genetic testing. The patients were grouped as syndromic and non-syndromic. The majority of individuals were of lower middle class, native ancestry and syndromic. There was a significant difference in the type of clefts regarding gender. There was no significant difference between bilateral and unilateral, between the side affected, right and left, or familial recurrence related to type of oral cleft. The risk factor familial recurrence was significantly higher among non-syndromic cases. Etiological factors were identified or suggested in 62.5% of the syndromic cases. There was a delay in diagnosis and in access to treatment in most cases. We concluded that gender, native ancestry and low family income represent risk factors. Furthermore, the distribution by cleft types and gender is similar to previous studies. The results can guide scientific investigations and care policies.

Rare variants found in clinical gene panels illuminate the genetic and allelic architecture of orofacial clefting

PURPOSE

Orofacial clefts (OFCs) are common birth defects including cleft lip, cleft lip and palate, and cleft palate. OFCs have heterogeneous etiologies, complicating clinical diagnostics because it is not always apparent if the cause is Mendelian, environmental, or multifactorial. Sequencing is not currently performed for isolated or sporadic OFCs; therefore, we estimated the diagnostic yield for 418 genes in 841 cases and 294 controls.

METHODS

We evaluated 418 genes using genome sequencing and curated variants to assess their pathogenicity using American College of Medical Genetics criteria.

RESULTS

9.04% of cases and 1.02% of controls had "likely pathogenic" variants (P < .0001), which was almost exclusively driven by heterozygous variants in autosomal genes. Cleft palate (17.6%) and cleft lip and palate (9.09%) cases had the highest yield, whereas cleft lip cases had a 2.80% yield. Out of 39 genes with likely pathogenic variants, 9 genes, including CTNND1 and IRF6, accounted for more than half of the yield (4.64% of cases). Most variants (61.8%) were "variants of uncertain significance", occurring more frequently in cases (P = .004), but no individual gene showed a significant excess of variants of uncertain significance.

CONCLUSION

These results underscore the etiological heterogeneity of OFCs and suggest sequencing could reduce the diagnostic gap in OFCs.

Genetics and orofacial clefts: a clinical perspective

Orofacial clefts (OFCs) are the most common congenital craniofacial anomaly seen in humans. Most OFCs are sporadic and isolated - these are thought to be multifactorial in origin. Chromosomal and monogenic variants account for the syndromic forms and for some of the non-syndromic inherited forms. This review discusses the importance of genetic testing and the current clinical strategy to deliver a genomics service that is of direct benefit to patients and their families.

Ambient temperature and major structural anomalies: A retrospective study of over 2 million newborns

BACKGROUND

Maternal exposure to ambient heat may be associated with congenital anomalies, but evidence is still limited.

OBJECTIVES

We aimed to estimate the association between maternal exposure to ambient heat during the 3-12 weeks post-conception (critical window of organogenesis) and risk of total and various diagnostic categories of major structural anomalies among live singleton births in the contiguous United States (US).

METHODS

We included data on 2,352,529 births with the first day of critical developmental windows falling within months of May through August from 2000 to 2004 across 525 US counties. We used a validated spatial-temporal model to estimate daily county-level population-weighted temperature. We used logistic regression to estimate the association between ambient temperature and risk of diagnostic categories of anomalies during the critical window after adjusting for individual and county-level factors. We conducted subgroup analysis to identify potential susceptible subpopulations.

RESULTS

A total of 29,188 anomalies (12.4 per 1000 births) were recorded during the study period. Maternal exposure to extreme heat (> 95th percentile) was associated with higher risk of total anomalies, central nervous system anomalies, and other uncategorized anomalies with an odds ratio (OR) of 1.05 (95 % CI: 1.00, 1.11), 1.17 (95 % CI: 1.01, 1.37), and 1.16 (95 % CI: 1.04, 1.29) compared with minimum morbidity temperature, respectively. The associations were homogeneous across subgroups defined by maternal age, maternal race/ethnicity, marital status, educational attainment, and parity, but were more pronounced among mothers residing in more socially vulnerable counties and births with multiple anomalies.

CONCLUSIONS

Among US live singleton births, maternal exposure to ambient heat may be associated with higher risk of total anomalies, central nervous system anomalies, and other uncategorized anomalies. We suggest additional research is carried out to better understand the relations between maternal heat exposure and congenital anomalies in the presence of global warming.