From the Desk of IJCP Group Editor-in-Chief children. If the results of the ultrasound exam are equivocal, it may be followed by CT. This approach is costeffective, reduces potential radiation risks and has excellent accuracy, with reported sensitivity and specificity of 94%. • Don’t recommend follow-up imaging for clinically inconsequential adnexal cysts. Simple cysts and hemorrhagic cysts in women of reproductive age are almost always physiologic. Small simple cysts in postmenopausal women are common, and clinically inconsequential. Ovarian cancer, while typically cystic, does not arise from these benign-appearing cysts. After a good quality ultrasound in women of reproductive age, don’t recommend follow-up for a classic corpus luteum or simple cyst
ORIGINAL RESEARCH Interferon IRF6 Gene Variants and the Risk of Isolated Cleft lip or Palate in South Indian Dravidian Population S Kishore Kumar*, MR Sukumar*, B Saravanan**, Arvind Ramanathan † , M Boominathan ‡ Abstract Nonsyndromic clefts of the lip and palate (CL, CP, CL/P) are among the most common congenital defects caused by multifactorial etiological factors that include both environmental and genetic factors. There is sufficient evidence to hypothesize that disease locus for this condition can be identified by candidate genes. The purpose of this study is to investigate the prevalence of mutation in exon 7 of IRF6 gene to determine whether this mutation is implicated in the South Indian Dravidian population. Material and methods: Blood samples were collected with informed consent from 10 subjects with nonsyndromic cleft lip/palate and genomic DNA was extracted from the blood samples, polymerase chain reaction was performed and the products were subjected to direct sequencing. Results: There was a significant positive association between the occurrence of homozygous valine polymorphic variant and isolated CL, CP and CL or CP (90%, n = 9) relative to heterozygous valine and isoleucine variant (10%, n = 1) in the present study. Conclusion: The study is clinically significant because it has for the first time identified the genetic status of exon 7 of IRF6 in Tamil speaking Dravidian population. Key words: Nonsyndromic cleft lip and palate, IRF6 gene variant, polymerase chain reaction Development of the head and face comprises of one of the most complex events during embryonic development, coordinated by a network of gene expressions that include transcription factors and signaling molecules, which confer polarity of cells. Disturbance of this tightly regulated network of signaling events may interfere with otherwise normal cellular function and consequently may result in the failure of meeting and fusion of the developing facial primordia, thereby causing orofacial cleft. The extent of orofacial cleft phenotype varies among the affected children with some having cleft lip (CL) or cleft palate (CP) (isolated CL or CP), while the others have cleft lip with cleft palate (CL/P). Clefts may involve either onehalf of the oral cavity or both and accordingly they are classified as unilateral or bilateral clefts. Such orofacial cleft may either occur as an isolated event (designated as nonsyndromic) or as a part of complex malformations (designated as syndromic). Nonsyndromic cleft makes about 70% of all orofacial clefts, while the remaining * Professor ** Reader, Dept. of Orthodontics † Principal, Investigator, Human Genetics Laboratory ‡ Postgraduate Student, Dept. of Orthodontics Sree Balaji Dental College and Hospital, Chennai Address for correspondence Dr S Kishore kumar E-mail: spkishorekumar@yahoo.co.in 30% are accounted for syndrome associated clefts. 1,26,29 The etiology seems complex 2,,3,9,11,12,16 but genetics plays a major role. 1,4,6,8,15 Various candidate genes have been associated with nonsyndromal cleft lip/palate in different populations, but Interferon regulatory factor-6 (IRF6) is strongly related in various populations on a consistent basis. 19,20,23,25,27,28 Identification of etiologic explanation for clefting has included extensive evaluation of genes. 22 IRF6 belongs to a family of nine transcription factors that share a highly-conserved helix-turn-helix DNA-binding domain. The DNA-binding domain is essential for IRF6 to bind the promoter region of the genes it regulates (activates). Mutations in IRF6 were first reported in van der Woude syndrome (VWS). 13 Investigation of the genetic status of IRF6 in nonsyndromic CL/P patients identified common polymorphic variant G>A at position 820 in the coding DNA of IRF6 gene. This causes the conversion of GTC to ATC and creates a valine→isoleucine substitution at amino acid 274 in the protein-binding domain of IRF6 gene. 29 GTC encoding valine amino acid has been found to be significantly associated with cleft in several populations. Material and Methods Indian Journal of Multidisciplinary Dentistry, Vol. 2, <strong>Issue</strong> 3, <strong>May</strong>-<strong>Jul</strong>y 2012 487
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