Mutational Analysis of Osteogenesis Imperfecta (OI) in Consanguineous Pakistani Families

Abstract

Brittle bone disease, or Osteogenesis Imperfecta (OI), is a heritable genetic disorder marked by severe bone fragility, osteoporosis, and low bone mineral density. This study investigated consanguineous Pakistani families showing autosomal recessive inheritance of OI. Blood samples (5–10 ml) were collected from both normal and affected individuals, including three normal and one affected member from Family A, and three normal and three affected members from Family B. Genomic DNA was extracted using the conventional phenol–chloroform method. Whole exome sequencing was performed for one affected individual (IV-5) and two obligate carriers (III-1 and III-2) from Family A to identify causative genes. Sanger sequencing was used to validate gene variants consistent with the patients’ clinical phenotypes and to determine segregation within the families. The analysis identified pathogenic variants in CREB3L1 (c.528C>T; p. Leu346Asp) and COL1A1 (c.540G>A; p. Leu133*) using specifically designed primers. Exome data were further filtered for homozygous variations using moon analysis, based on the autosomal recessive pattern of the disorder. Several genes with clinical features corresponding to the study subjects were reported. Overall, these findings are valuable for carrier detection and genetic counseling to help prevent transmission of the disease to future generations.