Cleft lip with or without cleft palate: frequency in different ethnic populations from the UCSF craniofacial clinic

Orofacial Cleft and Mandibular Prognathism-Human Genetics and Animal Models

Many complex molecular interactions are involved in the process of craniofacial development. Consequently, the network is sensitive to genetic mutations that may result in congenital malformations of varying severity. The most common birth anomalies within the head and neck are orofacial clefts (OFCs) and prognathism. Orofacial clefts are disorders with a range of phenotypes such as the cleft of the lip with or without cleft palate and isolated form of cleft palate with unilateral and bilateral variations. They may occur as an isolated abnormality (nonsyndromic-NSCLP) or coexist with syndromic disorders. Another cause of malformations, prognathism or skeletal class III malocclusion, is characterized by the disproportionate overgrowth of the mandible with or without the hypoplasia of maxilla. Both syndromes may be caused by the presence of environmental factors, but the majority of them are hereditary. Several mutations are linked to those phenotypes. In this review, we summarize the current knowledge regarding the genetics of those phenotypes and describe genotype-phenotype correlations. We then present the animal models used to study these defects.

Decreasing Incidence of Palatoplasty in the United States

INTRODUCTION

Cleft palate is amongst the most common birth defect across the world. Although its etiology is multifactorial, including genetic and environmental contributors, the investigators were interested in exploring whether its incidence was changing over time.

METHODS

The Nationwide Inpatient Sample database, the largest publically available healthcare database in the United States, was used to identify all primary palatoplasties performed under 2 years of age and births which occurred over a 17-year period from 1999 to 2015. The change in rate of palatoplasties and overall maternal demographics were assessed longitudinally using the chi-squared test. Significance level was set at P < 0.001.

RESULTS

A total of 13,808,795 pregnancies were reviewed during the time period, from 1999 to 2015, inclusively. A total of 10,567 primary palatoplasties were performed in that period of time reflecting an overall rate of 7.7 palatoplasties per 10,000 deliveries. Palatoplasty rates decreased across the study period from 9.5 per 10,000 in 1999 to 7.1 per 10,000 died/delivered pregnancies in 2015 which corresponds to an average compounded year-to-year decrease of 1.76%, P < 0.001.

CONCLUSIONS

The rate of primary palatoplasties, as a proxy for the rate of cleft palate prevalence, has been significantly decreasing over the last 2 decades and may represent improvements in early diagnosis in pregnancy, changing genetic or racial demographics, and/or environmental factors such as decreased maternal smoking in the US population. Future research may be directed at better understanding the definitive etiology of this decreasing prevalence of children undergoing primary cleft palate repairs in the United States.

Neural crest-specific deletion of Ldb1 leads to cleft secondary palate with impaired palatal shelf elevation

Background

LIM domain binding protein 1 (LDB1) is a transcriptional co-factor, which interacts with multiple transcription factors and other proteins containing LIM domains. Complete inactivation of Ldb1 in mice resulted in early embryonic lethality with severe patterning defects during gastrulation. Tissue-specific deletions using a conditional knockout allele revealed additional roles of Ldb1 in the development of the central nervous system, hematopoietic system, and limbs. The goal of the current study was to determine the importance of Ldb1 function during craniofacial development in mouse embryos.

Results

We generated tissue-specific Ldb1 mutants using Wnt1-Cre, which causes deletion of a floxed allele in the neural crest; neural crest-derived cells contribute to most of the mesenchyme of the developing face. All examined Wnt1-Cre;Ldb1^fl/- mutants suffered from cleft secondary palate. Therefore, we performed a series of experiments to investigate how Ldb1 regulated palate development. First, we examined the expression of Ldb1 during normal development, and found that Ldb1 was expressed broadly in the palatal mesenchyme during early stages of palate development. Second, we compared the morphology of the developing palate in control and Ldb1 mutant embryos using sections. We found that the mutant palatal shelves had abnormally blunt appearance, and failed to elevate above the tongue at the posterior domain. An in vitro head culture experiment indicated that the elevation defect was not due to interference by the tongue. Finally, in the Ldb1 mutant palatal shelves, cell proliferation was abnormal in the anterior, and the expression of Wnt5a, Pax9 and Osr2, which regulate palatal shelf elevation, was also altered.

Conclusions

The function of Ldb1 in the neural crest-derived palatal mesenchyme is essential for normal morphogenesis of the secondary palate.

Resource Utilization in Primary Repair of Cleft Lip

Objective

To determine national variations in resource utilization for primary repair of cleft lip, identify patient and institutional factors associated with high resource use, and estimate the current incidence of cleft lip in the United States.

Study Design

Retrospective analysis of a national, pediatric database (2009 Kids’ Inpatient Database [KID]).

Methods

Patients aged 1 year and younger were selected using international classification of disease codes for cleft lip and procedure codes for cleft lip repair. A number of demographic variables were analyzed, and hospital charges were considered as a measure of resource utilization.

Results

There were 1318 patients identified. The national incidence was 0.09%, with a male to female ratio of 1.8:1. Regional incidence varied from 0.07% (Northeast) to 0.10% (West). The mean age at surgery was 4.2 months. The average length of stay was 1.4 days. The national average hospital charge was $20,147, ranging from $14,635 (South) to $23,663 (West). Teaching hospitals charge an average of $9764 higher than nonteaching hospitals. The strongest predictor of charge was length of stay, increasing charge by $8102 for every additional hospital day ( P < .01).

Conclusion

Regional variations exist in resource utilization for primary cleft lip repair. Resource use is higher in the West and among teaching hospitals.