A MISSENSE MUTATION OF MSX1 GENE IN PAKISTANI FAMILIES WITH HYPODONTIA

Abstract

Objective: To understand the role of MSX1 gene in Pakistani families with hypodontia.

Study Design: Descriptive study.

Place and Duration of Study: This descriptive study was performed in Human Molecular Genetics (HMG) Laboratory of Baluchistan University of Information Technology, Engineering and Management Sciences (BUITEMS). The study was of 5 months duration.

Material and Methods: Peripheral blood sample of 5 ml was extracted intravenously from all affected individuals, normal siblings and their parents in 15ml falcon tubes containing 200μl EDTA. Human genomic DNA was extracted by using inorganic method from the blood leukocytes (samples) following a standardized protocol already established in Human Molecular Genetics (HMG) laboratory of BUITEMS. Two coding exons of MSX1 (NM_002448.3) were amplified and sequenced. Sequence analysis of the coding region of MSX1 gene is reveal through Bio Edit, Chromas and Seqman software’s.

Results: Hypodontia of permanent teeth of each affected family member was confirmed from history, clinical and radiographic examination. The clinical examination of Family 1 (proband I) revealed missing maxillary teeth 12, 18, 22, 28 and mandibular teeth 31, 41, 42 (FDI number system). The proband I-1 has also shown dental malformation of teeth and tongue tie. Family 2 (proband II) had missing maxillary lateral incisor 12, 22 (FDI
number system). Cephalometric analysis showed that proband I and proband II both had mild skeleton class-II malocclusion (ANB-6º, ANB-5º respectively) with normal vertical pattern. Dental cast analysis showed class-II dental relation with large midline diastema and anterior spaces in both affected proband. The coding region of MSX1 exons were sequenced and analyzed through Bio Edit, Chromas and Seqman software’s and a missense mutation was found. Here the transition of alanine-to-glycine lead to a substitution at amino acid position 40(c.119C>G p. Ala40Gly).

Conclusion: This genetic study revealed missense mutation (c.119C>G p.Ala40Gly) in exon 1 of MSX1 gene in Pakistani families with upper lateral hypodontia along with other dental anomalies including microdontia and tongue tie.