Tetrasomy 9p caused by idic (9) (pter----q13----pter).

Area of Science:

• Human Genetics
• Clinical Cytogenetics
• Developmental Biology

Background:

• Congenital malformations in infants necessitate detailed etiological investigations, including cytogenetic analysis.
• Chromosomal abnormalities are a significant cause of birth defects and developmental disorders.

Observation:

• A male infant presented with multiple congenital anomalies.
• Cytogenetic studies were performed on metaphase chromosomes from the infant's peripheral blood lymphocytes.
• Standard and differential staining techniques (GTG, CBG, G-11) were employed.

Findings:

• The infant's karyotype revealed an extra chromosome structurally similar to chromosome 9.
• Detailed banding analysis confirmed the presence of an isodicentric chromosome 9, specifically +idic(9)(pter----q13----pter).
• The complete karyotype was determined as 47,XY,+idic(9).

Implications:

• This case highlights the importance of precise cytogenetic diagnosis in identifying the cause of congenital malformations.
• Isodicentric chromosome 9 (idic(9)) is a rare chromosomal abnormality associated with a spectrum of developmental abnormalities.
• Further research is needed to understand the genotype-phenotype correlations in patients with idic(9).