The Lynch syndrome is hereditary nonpolyposis in patients with colorectal cancer. This diagnosis has implications for treatment and for the risk of cancer among family members. In this study of 1066 patients with newly diagnosed colorectal cancer, 23 patients and 52 family members were positive for Lynch syndrome mutations. Had the criteria of age and the presence or absence of a family history been used to select patients for genetic screening, many mutations would have remained undetected.

Routine screening for the Lynch syndrome among patients with colorectal cancer may be beneficial to patients and their family members.

In patients with persistent atrial fibrillation, amiodarone and sotalol were equally efficacious for conversion of the arrhythmia to sinus rhythm. However, amiodarone was clearly superior to sotalol for maintenance of sinus rhythm. The results establish amiodarone as the drug of choice for the management of atrial fibrillation.

Standard antibody screening does not detect recent infection in persons who have viremia but are antibody-negative. In North Carolina, nucleic acid amplification testing for HIV was added to the screening of 109,250 subjects who were tested during one year. A total of 23 acutely infected subjects were identified only with the use of this additional test.

The addition of nucleic acid amplification to standard screening tests for HIV improved the detection of cases by 3.9 percent and also detected the patients with acute infections at the most contagious stage.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a common cause of hyponatremia. This article describes two infants with a clinical picture of SIADH but with undetectable levels of arginine vasopressin. Each had a gain-of-function mutation in the V2 vasopressin receptor that changed arginine to cysteine or leucine in codon 137, causing constitutive activation of the receptor. The authors term this condition "nephrogenic syndrome of inappropriate antidiuresis."

A 49-year-old maintenance worker with a history of depression and previous reports of minor back pain is seen during four months of continuing low back pain. He has remained out of work for fear of worsening the injury. Magnetic resonance imaging two weeks after the onset of pain showed only mild degenerative changes in the lumbar region without spinal stenosis or disk collapse or extrusion. How should this patient be evaluated and treated?

Research to define the pathogenesis of psoriasis, a common inflammatory skin disorder, has considerably increased the general understanding of T-cell–mediated autoimmune disorders. Psoriasis is increasingly a prime target for new pathogenesis-oriented biologic therapies. The authors of this article review genetic, clinical, and pathogenic aspects of psoriasis and discuss their implications for new therapies.

A previously healthy 17-year-old boy presented to his primary care physician, reporting four days of low back pain, a temperature as high as 40°C, headache, diffuse myalgias, and vomiting. He lived in the central Midwest and was about to begin his senior year in high school.