Final answer:
Option a) Fanconi anemia is associated with missing thumbs, while Diamond-Blackfan anemia can present with triphalangeal thumbs. Neither thalassemia nor sickle cell anemia typically involves these thumb anomalies.
Step-by-step explanation:
The correct answer to the question about congenital anemias and their associated thumb anomalies is: a) Fanconi anemia; Diamond-Blackfan anemia.
Fanconi anemia is characterized by various congenital defects, including the possibility of missing thumbs or having thumbs with only one or two phalanges (instead of the normal three), which is known as radially displaced thumbs or absent thumbs. On the other hand, Diamond-Blackfan anemia is primarily a disease of the bone marrow that can also present with thumb anomalies, but unlike Fanconi anemia, it typically does not include missing thumbs, and triphalangeal thumbs (having three phalanges in the thumb rather than the usual two) sometimes occur.
It is important to note that neither thalassemia nor sickle cell anemia is typically associated with these specific physical anomalies. Both of these conditions are hemoglobinopathies characterized by issues with hemoglobin synthesis, leading to ineffective erythropoiesis and reduced oxygen-carrying capacity of the blood, among other symptoms.