H. The patient is diagnosed with Wilson disease, an autosomal-recessive disorder that causes decreased copper efflux from the liver due to mutations in the hepatic copper transport protein ATP7B. This results in copper leakage into the blood, leading to deposition in various organs such as the brain, eyes, kidney, and skin. As a consequence, liver and kidney damage, neurologic effects, and corneal changes occur due to excessive copper levels. The treatment for this condition involves administering the metal chelator penicillamine, with zinc supplementation often being necessary. On the other hand, Graves disease causes hyperthyroidism, hereditary hemochromatosis is characterized by iron overload, Keshan disease is a result of selenium deficiency, and selenosis is caused by excess selenium. Menkes syndrome, caused by mutations in the intestinal copper transport protein ATP7A, leads to a systemic copper deficiency. 

A 52-year-old female patient presents with unintended changes in skin pigmentation, resulting in a tanned appearance. Physical examination reveals hyperpigmentation, hepatomegaly, and mild scleral icterus. Laboratory tests indicate elevated serum transaminases (liver function tests) and fasting blood glucose, while results of other tests are pending. This patient is diagnosed with hereditary hemochromatosis, a condition characterized by iron overload. The primary cause of this disorder is abnormally low levels of hepcidin due to mutations in the HFE (high iron) gene. Hepcidin regulates the degradation of ferroportin, the only known iron export protein in humans. A decrease in hepcidin results in increased iron levels, leading to hyperpigmentation and hyperglycemia, also known as "bronze diabetes." The treatment for hereditary hemochromatosis involves phlebotomy or the use of iron chelators. Pending laboratory tests would likely show an increase in serum iron and transferrin saturation. 

In terms of genetic information storage and expression, nucleic acids are essential. There are two chemically distinct types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). DNA serves as the repository of genetic information (genome) and is present not only in the chromosomes of the nucleus in eukaryotic organisms but also in the mitochondria and chloroplasts of plants. Prokaryotic cells lack nuclei but possess a single chromosome and may contain nonchromosomal DNA in the form of plasmids. The genetic information stored in DNA is replicated and transmitted to daughter cells through DNA replication. The DNA contained in a fertilized egg carries the instructions for organism development, which involves the production of billions of specialized cells. DNA must be able to replicate accurately during cell division and selectively express the contained information. Transcription, the synthesis of RNA, initiates the expression of genetic information, while translation, the synthesis of proteins, completes gene expression. Chapter 33 discusses the regulation of gene expression. This flow of information from DNA to RNA to protein is known as the "central dogma" of molecular biology, applicable to all organisms except certain viruses that utilize RNA as their genetic information repository. 

DNA structure is the next topic discussed.
Correct answer = H. The patient has Wilson disease, an autosomal-recessive disorder that decreases copper efflux from the liver because of mutations to the hepatic copper transport protein ATP7B. Some copper leaks into the blood and is deposited in the brain, eyes, kidney, and skin. This results in liver and kidney damage, neurologic effects, and corneal changes caused by the excess copper. Administration of the metal chelator penicillamine is the treatment. [Note: Because zinc is also chelated, supplementation with zinc is common.] Graves disease results in hyperthyroidism. Hereditary hemochromatosis is a disorder of iron overload. Keshan disease is the result of selenium deficiency, whereas selenosis is caused by selenium excess. Menkes syndrome is the result of a systemic deficiency in copper as a result of mutations to ATP7A, an intestinal copper transport protein.
9.10. A 52-year-old female is seen because of unplanned changes in the pigmentation of her skin that give her a tanned appearance. Physical examination shows hyperpigmentation, hepatomegaly, and mild scleral icterus. Laboratory tests are remarkable for elevated serum transaminases (liver function tests) and fasting blood glucose. Results of other tests are pending.
Correct answer = B. The patient has hereditary hemochromatosis, a disease of iron overload that results from inappropriately low levels of hepcidin caused primarily by mutations to the HFE (high iron) gene. Hepcidin regulates ferroportin, the only known iron export protein in humans, by increasing its degradation. The increase in iron with hepcidin deficiency causes hyperpigmentation and hyperglycemia (“bronze diabetes”). Phlebotomy or use of iron chelators is the treatment. [Note: Pending lab tests would show an increase in serum iron and transferrin saturation.]
UNIT VII Storage and Expression of Genetic Information
DNA Structure, Replication, and Repair
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I. OVERVIEW
Nucleic acids are required for the storage and expression of genetic information. There are two chemically distinct types of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid ([RNA] see Chapter 31). DNA, the repository of genetic information (or, genome), is present not only in chromosomes in the nucleus of eukaryotic organisms, but also in mitochondria and the chloroplasts of plants. Prokaryotic cells, which lack nuclei, have a single chromosome but may also contain nonchromosomal DNA in the form of plasmids. The genetic information found in DNA is copied and transmitted to daughter cells through DNA replication. The DNA contained in a fertilized egg encodes the information that directs the development of an organism. This development may involve the production of billions of cells. Each cell is specialized, expressing only those functions that are required for it to perform its role in maintaining the organism. Therefore, DNA must be able not only to replicate precisely each time a cell divides, but also to have the information that it contains be selectively expressed. Transcription (RNA synthesis) is the first stage in the expression of genetic information (see Chapter 31). Next, the code contained in the nucleotide sequence of messenger RNA molecules is translated (protein synthesis; see Chapter 32), thus completing gene expression. The regulation of gene expression is discussed in Chapter 33.
The flow of information from DNA to RNA to protein is termed the “central dogma” of molecular biology (Fig. 30.1) and is descriptive of all organisms, with the exception of some viruses that have RNA as the repository of their genetic information.
II. DNA STRUCTURE