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Diagnosis: Robertsonian
Translocation Carrier
ISCN: 45,XX,der(13;14)(q10;q10) or 45,XX,rob(13;14)(q10;q10)
Discussion:
This patient had a child who was born with clinical findings suggestive
of Trisomy 13. Chromosome analysis of the newborn revealed Trisomy 13
secondary to a Robertsonian translocation. Chromosome analyses of this
patient and her husband were performed to see if either of them carried
a Robertsonian translocation; this patient's husband had normal chromosomes,
while she was shown to be a Robertsonian translocation carrier. Additional
questioning of the parents revealed that this couple had two phenotypically
normal children and a history of multiple spontaneous miscarriages. There
was no history of birth defects in either family.
Robertsonian translocations are translocations that occur between the
short arms of two acrocentric chromosomes (13, 14, 15, 21, 22). Robertsonian
translocations are present in approximately 1/1,000 newborns. The most
common Robertsonian translocation involves chromosomes 13 and 14 [rob(13;14)];
this accounts for approximately 75% of all Robertsonian translocations.
The second most common Robersonian translocation is the rob(14;21) which
accounts for approximately 10% of all Robertsonian translocations. Newborn
balanced carriers of Robertsonian translocations are phenotypically normal.
However, when these carriers become adults, they will have an increased
risk of infertility and miscarriage, as well as having an increased risk
of having offspring with an unbalanced Robertsonian translocation.
Genetic counseling of this patient and her husband was recommended to
explain why their daughter had trisomy 13, what the recurrance rish was
for future pregnancies, and to determine if other family members were
carriers and also at risk.
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