A new mutation of the arginine vasopressin-neurophysin II gene in a family with autosomal dominant neurohypophyseal diabetes insipidus.

Familial neurohypophyseal diabetes insipidus (FNDI) is an autosomally dominant inherited disorder with a typical onset at one to six years of age. The genetic locus of FNDI is the arginine vasopressin-neurophysin II (AVP-NPII) gene. The gene encoding the precursor hormone (prepro-AVP-neurophysin II) is located in the chromosomal region 20p13 and contains three exons. Mutations that cause FNDI have been found to occur within the signal peptide of the prepro-AVP-neurophysin II precursor, within the coding sequence for neurophysin II and the vasopressin-coding sequence. A family (four members with FNDI, two without FNDI) in three consecutive generations was investigated. Index case was a now 22-year old man with a history of severe polyuria (18 L/day) and polydipsia first recognized at about 4-5 months of age. The arginine vasopressin-neurophysin II gene was investigated by direct sequencing of PCR products amplified from each exon. Subsequently, a restriction analysis was performed to verify the sequencing results. The affected individuals were found to have a missense mutation in exon 2 at nucleotide position 1887 (G to C) of the AVP-NPII gene. Using both restriction enzyme digestion and sequence analysis, the mutation was found in all affected family members, but not in the unaffected members studied. This mutation (1887 G to C) represents a novel mutation of the AVP-NPII gene.

Diagnostic strategies and surgical procedures in persistent or recurrent primary hyperparathyroidism.

The incidence of persistent or recurrent primary hyperparathyroidism reported in the literature lies between 1 and 10%. The main causes are represented by atypical locations or incorrect diagnosis of primary parathyroid hyperplasia. Since primary parathyroidectomy by an experienced surgeon has a success rate of 95%, there is no need for extended imaging studies prior to initial bilateral exploration. After confirming diagnosis of persistent or recurrent hyperparathyroidism exact localization studies are necessary. The most important procedures are ultrasonography, magnetic resonance imaging, technetium Tc99m sestamibi scintigraphy with a combined sensitivity of approximately 90%. In case of negative imaging results selective venous catheterization before reoperation can be performed. Reoperation by an experienced surgeon will be successful in 95% of cases.

[Clinical and endocrine diagnosis of pheochromocytoma]. / Klinik und endokrine Diagnostik des Phäochromozytoms.

Pheochromocytomas are catecholamine-producing tumors, representing one of the most important causes of secondary hypertension. The classification of these tumors considers both sporadic and familial forms, intra- and extraadrenal localization as well as the dignity. Familial pheochromocytomas are primarily seen under the conditions of multiple endocrine neoplasia, von Hippel-Lindau disease or neurofibromatosis type 1. The list of clinical symptoms includes hypertension, which can be both continuous or intermittent, headache, tachycardia and sweating. It is most important to standardize the pre-analytical procedures, i.e. control for sampling conditions and adequate choice of parameters in plasma or urine. For screening sensitive methods will be employed (free catecholamines in 24h-urine) and for confirmation of the diagnosis, specific procedures are performed (Clonidine test, MIBG-scintigraphy). The endocrinological and biochemical procedures are completed by molecular genetic techniques in familial pheochromocytoma.