A 5-day-old girl is brought to the office by her adoptive parents for her first newborn visit. The girl has been doing well. The parents are concerned about her risk of having hemophilia A. The birth father and his brother (the paternal uncle) have hemophilia A. The birth mother does not, and there is no history of bleeding in her family, including in male relatives. The girl is well-appearing and has no abnormalities on examination. Which of the following is the most appropriate response?

Question

A 5-day-old girl is brought to the office by her adoptive parents for her first newborn visit.  The girl has been doing well.  The parents are concerned about her risk of having hemophilia A.  The birth father and his brother (the paternal uncle) have hemophilia A.  The birth mother does not, and there is no history of bleeding in her family, including in male relatives.  The girl is well-appearing and has no abnormalities on examination.  Which of the following is the most appropriate response?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c0ec_6126_8f63_91b95fe67485_MD0005_00 Hemophilia A is an X-linked recessive disorder that occurs almost exclusively in males. Females are usually asymptomatic carriers of the disease, although mild bleeding is possible in carriers. A female may acquire hemophilia in the rare situation in which her father has hemophilia and her mother is a carrier who transmits the abnormal allele to her. This patient's birth mother has no family history of bleeding, including in male relatives; therefore, it is highly unlikely that the birth mother is a carrier. A father who has hemophilia will transmit the abnormal allele to all his daughters and, consequently, they will be carriers of the disease. Sons will be unaffected, as they receive only a single, normal allele on the X chromosome inherited from their mother. If the mother is a carrier, her daughters have a 50% chance of being carriers, and her sons have a 50% chance of having hemophilia. Educational objective: Hemophilia A is an X-linked recessive disorder that occurs almost exclusively in males. Daughters born to an affected father and a normal mother will be carriers. Sons born to a carrier mother have a 50% chance of having hemophilia. References: Hemophilia: a practical approach to genetic testing. (http://www.ncbi.nlm.nih.gov/pubmed/16295028)

A 5-Day-Old Girl Is Brought to the Office by Her