cleft lip

Microform Cleft Lip

Catherine Carlile, BS; Alix D’Angelo, MGC; Steven Blackwell, MD; and Lynnette Mazur, MD, MPH

An 8-week-old boy presented to clinic for a checkup. He was born at full term, weighed 2900 g at birth, and had no difficulty feeding or breathing. His mother did not have diabetes and was not overweight, and she did not smoke, use alcohol or drugs, or use medications or herbal supplements during pregnancy. The family history was negative for cleft lip and/or palate (CL/P).

Findings from the physical examination revealed a vertical groove on the right philtrum and notching of the vermilion-cutaneous junction, the vermilion-mucosal junction, and the upper alveolar ridge. Nasal flattening was also present. (Figures 1 and 2) There were no palatal defects, and the rest of the physical examination findings were unremarkable. 


The findings of the examination suggested a microform cleft lip (CL). The cardinal features of a microform CL are minimal nasal deformity, a philtral ridge or groove from vermilion to nostril sill, indented free mucosal margin, and a notched vermilion-cutaneous junction.1 Some microform CLs are so small that they may go undiagnosed. Older terms such as occult, minor, minimal, forme fruste, and congenital healed CL are no longer used to describe the condition.

Although CL/P results from incomplete closure of lateral and median palatal shelves early in gestation, a microform CL results from failure of complete mesodermal penetration into an intact ectodermal envelope rather than the previous theory of failed fusion of the medial nasal process and maxillary prominence.  

The prevalence of CL/P is approximately 1 in 700 live births, but the prevalence of a microform CL is unknown.2 Environmental contributing factors that may increase risk of CL/P include maternal smoking, maternal binge alcohol use, pregestational diabetes, teratogens such as retinoic acid, and seizure medications such as phenytoin and valproic acid.3-5 

Isolated microform CL is not associated with feeding and speech difficulties, but referral to a craniofacial specialist for evaluation is indicated for longitudinal care to monitor dentofacial growth and to assess need for surgery. Surgery in infancy may leave a less notable scar than surgery performed later in childhood.6 

A microform CL is the expression of defective development of the primary palate, so abnormalities of the teeth are expected. These may include hypodontia (missing teeth), hyperdontia (supernumerary teeth), abnormal size/shape and position of teeth, and impaction. Therefore, future dental care will be important.  

A large cohort study showed that the recurrence risk among siblings of a proband with isolated bilateral CL/P was 4.6%, compared with 2.5% for siblings of a proband with a unilateral defect. However, the authors found no studies on recurrence risks for a microform CL.7 

Although some clinicians recommend preconceptual folate supplementation for prevention of CL/P, a meta-analysis on supplementation failed to show any preventative effect.8

Catherine Carlile, BS; Alix D’Angelo, MGC; Steven Blackwell, MD; and Lynnette Mazur, MD, MPH, are from the University of Texas Health Science Center at Houston.


1.Onizuka T, Hosaka Y, Aoyama R, Takahama H, Jinnai T, Usui Y, et al. Operations for microforms of cleft lip. Cleft Palate Craniofac J. 1991;28(3):293-300.

2.Dixon MJ, Marazita ML, Beaty TH, Murray JC. Cleft lip and palate: understanding genetic and environmental influences. Nature Rev Genet. 2011;12(3):167-178. 

3.Shi M, Wehby GL, Murray JC. Review on genetic variants and maternal smoking in the etiology of oral clefts and other birth defects. Birth Defects Res C Embryo Today. 2008;84(1):16-29. 

4.DeRoo LA, Wilcox AJ, Drevon CA, Lie RT. First-trimester maternal alcohol consumption and the risk of infant oral clefts in Norway: a population-based case-control study. Am J Epidemiol. 2008;168(6):638-646. 

5.Jentink J, Loane MA, Dolk H, et al. Valproic acid monotherapy in pregnancy and major congenital malformations. N Engl J Med. 2010;362(23):2185-2193. 

6.Li H, Yin N, Song T, Wang Y. New technique for correction of the microform cleft lip using trans/intraoral approach. Indian J Surg. 2014;76(5):415-418.

7.Grosen D, Chevrier C, Skytthe A, et al. A cohort study of recurrence patterns among more than 54,000 relatives of oral cleft cases in Denmark: support for the multifactorial threshold model of inheritance. J Med Genet. 2010;47(3):162-168.

8.De-Regil LM, Peña-Rosas JP, Fernández-Gaxiola AC, Rayco-Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev. 2015;12:CD007950.di:10.100214651858.CD007950.pub3.