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Familial partial monosomy 5p and trisomy 5q; three cases due to paternal pericentric inversion 5 (p151q333)
Insights
A family experienced recurrent pregnancy losses and congenital malformations due to a chromosomal rearrangement involving chromosome 5. This genetic abnormality led to partial monosomy 5p and partial trisomy 5q in affected infants.
Area of Science:
- Human Genetics
- Clinical Dysmorphology
- Cytogenetics
Background:
- Recurrent pregnancy loss and congenital anomalies can stem from complex chromosomal rearrangements.
- Identifying the specific genetic mechanisms is crucial for genetic counseling and understanding developmental disorders.
Observation:
- A family presented with a history of 9 pregnancies resulting in 2 healthy children, 4 miscarriages, and 3 infants with severe multiple congenital malformations.
- Affected infants exhibited features including bird-headed appearance, growth deficiency, microcephaly, micrognathia, and a cat-like cry.
- Two affected siblings had lethal cardiac malformations, while the third had a bicuspid aortic valve.
Findings:
- Karyotype analysis revealed a derivative chromosome 5 (46,XX,rec(5),dupq,inv(5)(p151q333)pat) in affected offspring, causing partial monosomy 5p and partial trisomy 5q.
- The father and one healthy sibling carried a pericentric inversion of chromosome 5 (46,XY,inv(5)(p151q333)).
- The observed clinical phenotype partially aligns with both partial 5p monosomy and partial 5q trisomy syndromes.
Implications:
- This case highlights the role of parental chromosomal inversions in generating unbalanced rearrangements leading to severe congenital anomalies and pregnancy loss.
- Understanding these complex rearrangements is vital for accurate genetic diagnosis and risk assessment in families with recurrent miscarriages or malformed offspring.
- Further research can elucidate the specific contributions of partial 5p monosomy and 5q trisomy to the observed phenotype.
Abstract:
A family is described in which the mother's 9 pregnancies ended in the birth of 2 healthy girls, 4 spontaneous abortions and 3 infants with multiple congenital malformations as bird-headed appearance, pre- and postnatal growth deficiency, microcephaly, micrognathia with small mouth and cat-like cry. Two of the three affected sibs had complex cardiac malformations incompatible with life; the third had a bicuspid aortic valve. Chromosomal investigation revealed an abnormal karyotype: 46,XX,rec(5),dupq,inv(5)(p151q333)pat, leading to a partial monosomy 5p and partial trisomy 5q. A large pericentric inversion of chromosome 5 was found in the father: 46,XY,inv(5)(p151q333) as well as in the firstborn healthy female sib. The clinical features partly fit the partial monosomy 5p as well as the partial trisomy 5q syndrome.