Familial t(4;13) with abnormal offspring in three generations

Area of Science:

• Genetics
• Developmental Biology
• Pediatrics

Background:

• Reciprocal translocations can lead to unbalanced chromosomal rearrangements in offspring, resulting in congenital anomalies.
• Familial inheritance of balanced translocations poses a risk for recurrent miscarriages or affected live births.
• Accurate cytogenetic analysis is crucial for diagnosing complex genetic disorders and understanding inheritance patterns.

Observation:

• A newborn female presented with severe intrauterine growth retardation, microcephaly, cleft lip and palate, absent thumbs, cardiac defects, pulmonary hypoplasia, and gastrointestinal malrotation.
• Karyotype revealed a 46,XX,13q+ constitution, resulting from a paternal t(4;13)(q25;q32) translocation, leading to deletion of 13q and duplication of 4q.
• The paternal grandmother and great-grandmother carried the balanced translocation and had previously given birth to infants with multiple congenital anomalies, including thumb abnormalities.

Findings:

• The patient's phenotype is consistent with a deletion on chromosome 13 (del(13q)) and duplication on chromosome 4 (dup(4q)).
• The identified chromosomal abnormality, t(4;13)(q25;q32), is paternally inherited and has manifested in multiple generations with varying degrees of severity.
• Comparison with the Niebuhr map of chromosome 13 aids in correlating specific deletions with observed clinical features.

Implications:

• This case underscores the phenotypic variability associated with dup(4q)/del(13q) syndrome and the importance of detailed cytogenetic mapping.
• Early genetic counseling and prenatal diagnosis are vital for families with a history of balanced translocations.
• Further research into the specific genes within the deleted and duplicated regions of chromosomes 4 and 13 may elucidate the precise mechanisms underlying these congenital anomalies.