sSMC

sSMC characterizes small supernumerary marker chromosomes (sSMCs), with emphasis on chromosome 15‑derived sSMCs in the context of male infertility.

Key Features:

• G-banding Analysis: Uses G-banding for initial cytogenetic identification and structural characterization of sSMCs.
• Chromosomal Microarray Analysis (CMA): Employs CMA to determine genomic content of sSMCs and can detect focal copy-number changes such as a 0.44-Mb microduplication at 6q25.3q26.
• Fluorescence In Situ Hybridization (FISH): Applies FISH with centromere-specific probes for chromosomes 13/21, 14/22, and 15 to ascertain sSMC origin and can confirm structures such as an inverted duplicated chromosome 15(q11.2).
• Heterochromatin Analysis: Investigates presence of heterochromatin within sSMCs and its potential to disrupt meiosis and impair spermatogenesis.

Scientific Applications:

• Infertility Diagnosis and Management: Characterizes sSMCs in infertile males, including cases with oligoasthenoteratozoospermia, to inform reproductive options such as intracytoplasmic sperm injection (ICSI).
• Clinical Genetic Counseling: Identifies carriers of sSMCs to provide molecular cytogenetic information relevant for genetic counseling and reproductive decision-making.

Methodology:

Integrates G-banding, chromosomal microarray analysis (CMA), and fluorescence in situ hybridization (FISH), together with literature reviews and database searches including the sSMC database.