New susceptibility variants to narcolepsy identified in HLA class II region.

Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness, cataplexy and rapid eye movement sleep abnormalities, is tightly associated with human leukocyte antigen HLA-DQB1*06:02. DQB1*06:02 is common in the general population (10-30%); therefore, additional genetic factors are needed for the development of narcolepsy. In the present study, HLA-DQB1 in 664 Japanese narcoleptic subjects and 3131 Japanese control subjects was examined to determine whether HLA-DQB1 alleles located in trans of DQB1*06:02 are associated with narcolepsy. The strongest association was with DQB1*06:01 (P = 1.4 × 10(-10), odds ratio, OR = 0.39), as reported in previous studies. Additional predisposing effects of DQB1*03:02 were also found (P = 2.5 × 10(-9), OR = 1.97). A comparison between DQB1*06:02 heterozygous cases and controls revealed dominant protective effects of DQB1*06:01 and DQB1*05:01. In addition, a single-nucleotide polymorphism-based conditional analysis controlling for the effect of HLA-DQB1 was performed to determine whether there were other independent HLA associations outside of HLA-DQB1. This analysis revealed associations at HLA-DPB1 in the HLA class II region (rs3117242, P = 4.1 × 10(-5), OR = 2.45; DPB1*05:01, P = 8.1 × 10(-3), OR = 1.39). These results indicate that complex HLA class II associations contribute to the genetic predisposition to narcolepsy.

Lethal Arrhythmia Induced by Severe Hypokalemia with Primary Aldosteronism: A Case Report and Literature Review.

A 26-year-old woman experienced sudden loss of consciousness with respiratory arrest while engaged in a heated conversation shortly after consuming a carbohydrate-rich meal; she was resuscitated immediately. Severe hypokalemia became evident and was deemed to have caused lethal arrhythmia. She was diagnosed with a left aldosterone-producing adenoma and achieved remission following partial adrenalectomy. Primary aldosteronism is frequently complicated by hypokalemia; however, hypokalemia-induced lethal arrhythmias are rare. Clinicians should recognize that primary aldosteronism can potentially cause sudden death in apparently healthy individuals; hence, an early diagnosis and proper treatment are critical.

Segmental low-density area on contrast-enhanced CT is a possible clue to diagnosing branch artery fibromuscular dysplasia.

Summary: Fibromuscular dysplasia can cause renovascular hypertension. Since fibromuscular dysplasia may be underdiagnosed, precise diagnosis and management are crucial, especially for young women. A 20-year-old woman with hypertension and hypokalemia was referred to our hospital for further evaluation of secondary hypertension. At the previous hospital, her blood pressure was 160/110 mmHg and the serum potassium level was 2.9 mEq/L. The equilibrium phase on contrast-enhanced computed tomography revealed a low-density area in the upper median portion of the right kidney. On admission to our hospital, her blood pressure was 141/96 mmHg under 5 mg of amlodipine. Laboratory tests revealed plasma renin activity of 11.3 ng/mL/h and plasma aldosterone concentration of 117.1 pg/mL. Renal venous sampling of active renin concentration showed a right-to-left renin ratio of 3.13, confirming a significant increase in renin secretion from the right kidney. Selective reno-angiography detected focal stenosis with adjacent aneurysmal dilation and tortuosity in the proximal branch of the right renal artery. She was diagnosed with branch artery fibromuscular dysplasia and successfully treated with percutaneous transluminal angioplasty. After the treatment, she was free from hypertension and hypokalemia without any medications. Since branch artery fibromuscular dysplasia is sometimes difficult to diagnose, contrast-enhanced computed tomography can be a promising diagnostic tool as shown in this case. Concerning treatment, our patient was treated with percutaneous transluminal angioplasty, which should be considered for women of reproductive age because recommended antihypertensive medications can be teratogenic even in the first trimester of pregnancy. Learning points: Although branch artery fibromuscular dysplasia (FMD) is sometimes difficult to diagnose, it should be considered in patients with high-renin, high-aldosterone hypertension. Branch artery FMD can present with a low-density area of the kidney on contrast-enhanced computed tomography, as shown in this case. Percutaneous transluminal angioplasty (PTA) can be an appropriate treatment for branch artery FMD, especially in young female patients. PTA may immediately improve hypertension and hypokalemia without the need for medications.