[Molecular characterisation of a kindred with MEN2A and clinical implications]

INTRODUCTION

MEN2A is an autossomal dominant cancer syndrome characterised by the presence of medullary thyroid cancer, pheochromocytoma and primary hyperparathyroidism. Germline mutations of the RET protooncogene constitute the molecular defect and can be identified in affected individuals. Genetic screening of family members at risk allows early diagnosis and preventive measures before the appearance of the disease. We present a family with several members affected with MEN2A, their molecular characterisation and the clinical implications of genetic testing.

POPULATION AND METHODS

We studied 18 members distributed among three generations of a family of which four members were clinically affected with MEN2A and cutaneous lichen amyloidosis. RET gene mutations were screened for in affected individuals and their offspring by PCR-RFLP techniques.

RESULTS

Genetic testing revealed a point mutation at codon 634 (TGC>TGG), in the heterozygous state, in all affected individuals. The same mutation was also found in a five years old asymptomatic child which after total thyroidectomy showed to have multifocal medullary thyroid carcinoma.

DISCUSSION

Genetic screening is the most suitable method for pre-symptomatic diagnosis of MEN2A allowing an efficient and early identification of individuals who will later develop the disease. These can be monitored more closely and be submitted to a prophylactic thyroidectomy before the appearance of medullary thyroid carcinoma. The ideal moment for this intervention is still under discussion although the results of this study suggest that it should be undertaken before the age of five.

The hyperparathyroidism-jaw tumour syndrome in a Portuguese kindred

The hyperparathyroidism-jaw tumour (HPT-JT) syndrome is an autosomal dominant disease characterized by the occurrence of parathyroid tumours and fibro-osseous tumours of the jaw bones. Some HPT-JT patients may also develop renal abnormalities, which include Wilms' tumours, hamartomas and polycystic disease. The HPT-JT gene has been mapped to chromosome 1q25-q31, and we report the clinical and genetic findings in a kindred from central Portugal. HPT-JT was observed in six members from three generations; all had primary hyperparathyroidism (five had parathyroid adenomas, one a parathyroid carcinoma). Ossifying jaw fibromas affecting the maxilla and/or mandible were observed in 5/6. Renal cysts (<2.5 cm) were observed in four. Genetic studies using 18 polymorphic loci from chromosome 1q25-q31, together with leukocyte DNA from 11 family members and tumour DNA from three parathyroids (two adenomas and one carcinoma), revealed loss of tumour heterozygosity in the parathyroid carcinoma only, and the retained haplotype was found to cosegregate with the disease in the six affected members. A new Portuguese kindred with the HPT-JT syndrome that maps to chromosome 1q25-q31 has been identified, and these findings will help in the further characterization of this inherited disorder.

[deficiency of growth hormone in children. Re-evaluation after therapeutic completion]

OBJECTIVE

To assess GH secretion in young adults treated with GH replacement therapy in childhood.

PATIENTS AND METHODS

From the 38 patients who concluded treatment with GH, we studied 20 (52.6%), 9 girls and 11 boys. Thirteen had Growth Hormone Deficiency (GHD)-65%, while 7 had Multiple Pituitary Hormone Deficiency (MPHD)-35%. The patients were retested within 6 months to 6 years after completing GH therapy. The mean age (+/- SD) at retesting was 18.1 +/- 2.6 years for those with GHD and 20.8 +/- 2.8 for those with MPHD. At reassessment we performed two provocative tests: insulin tolerance test (ITT) and clonidine test.

RESULTS

Seven of the 20 patients retested, retained GH deficiency. Of the 13 patients with GHD, only one maintained the deficiency, while of the 7 patients with MPHD, 6 maintained the deficiency.

CONCLUSION

Young adults with GH deficiency treated with this hormone should be retested in order to identify those who are truly GH insufficient adults and may benefit from replacement therapy.

[Kidney transplantation in patients with type I and type II diabetes mellitus]

A total of 618 patients with end-stage renal disease received kidney transplants between 1980 and September 1996. Twenty eight of them were diabetics. Better results were achieved for type 1 diabetic patients than for type 2 (mortality: 5.9% vs 27.3%; functioning graft: 88.2% vs 72.7%). The morbility was also higher in those patients (infections: 81.8% vs 29.4%; vascular complications: 45.5% vs 17.6%). Actuarial patient and graft survival were lower for type 2 than for non diabetic patients. For type 1 diabetics the results are similar to those for non diabetics. Better results can probably be achieved by restricting the selection criteria. The decision to transplant or maintain on dialysis should be made on a case by case basis.

[Craniocerebral imaging in children with short stature]

OBJECTIVE

To analyse the type and frequency of cranial CT and NMR imaging anomalies in children of short stature.

PATIENTS AND INTERVENTIONS

We studied 57 children of short stature with a mean age (+/-SD) of 10.1 +/- 3.8 years, 34 boys and 23 girls, all of them with auxometric criteria of GH deficiency. After studying the pituitary function and determination of karyotype in the girls, the children were classified in to five groups:-Isolated GHD (IGHD) (n = 32), multiple pituitary hormone deficiency (MPHD) (n = 6), neurosecretory dysfunction (NSD) (n = 8), Turner syndrome (n = 7) and idiopathic short stature (ISS) (n = 4). The imaging methods used were cranial CT or NMR.

RESULTS

Of the 57 children studied the CT/NMR was abnormal in 37(64.9%) children. We found anomalies in 65.6% of IGHD patients, 62.5% of NSD patients, 100% of MPHD patients and 57.1% and 25% in the Turner s. patients and ISS patients respectively. The most frequent anomaly was hypoplastic pituitary found in 50% of IGHD patients, 37.5% of NSD patients and 33.3% of MPHD patients. None of the cases of Turner s. or ISS had hypoplastic pituitary. An empty sella was the second most frequent anomaly found in 7 patients (IGHD-3, MPHD-3, DNS-1). Of the 25 children in which NMR was performed, 8 had hypoplastic pituitary and stalk and 2 had interruption of the pituitary stalk and ectopic neurohypophysis.

CONCLUSION

These results strengthen the necessity for CT/NMR imaging in children of short stature which, besides allowing identification of tumors, also permits the diagnosis of idiopathic GHD because of its frequent association with cranial imaging anomalies, mainly hypoplastic pituitary.

[The prevalence of hypertension in acromegaly]

AIM

To estimate the prevalence of hypertension (HT) in a group of patients with acromegaly at the moment of diagnosis and after treatment.

PATIENTS AND METHODS

Fifty-seven patients, 43 females and 14 males with a mean age of 45.19 +/- 11.9 years were studied retrospectively. In the last visit 9 patients (15.7%) were in remission and 47 (84.2%) had active acromegaly. We considered hypertensive the patients with systolic BP > or = 140 and/or diastolic BP > or = 90 mmHg. Hypertension was classified in four stages:- mild, moderate, severe and very severe.

RESULTS

The prevalence of hypertension at the moment of diagnosis was 35%. The hypertensive patients had a mean age of 51.75 +/- 9.3 years and normotensive patients 41.65 +/- 11.6 years (p < 0.001). In females the prevalence of HT was 27.9% and in males it was 57% (p = NS). In hypertensive patients (n = 20), the mean BP was 159 +/- 15 (syst.)/97.2 +/- 9.8 (diast.), 16 patients (80%) had mild to moderate HT and the remainder had severe (n = 2) and very severe (n=1) HT. In the last visit, 22.2% of patients were cured and 46.8% of those with active acromegaly were hypertensive. None of the patients cured and initially normotensive developed HT; among those that were hypertensive (n = 3), 2 remained hypertensive and 1 became normotensive. Among patients with active acromegaly and initially normotensive, 7 developed HT 4.85 +/- 2.03 years later; of those hypertensive at diagnosis (n = 16), only one became normotensive. The last case was 27 years old. The patients that remained hypertensive had a mean age of 53.8 +/- 6.85 years (41-62 years).

CONCLUSIONS

The prevalence of hypertension at the moment of diagnosis was 35%, similar to the majority of studies published and higher than the general population. The hypertensive patients were significantly older the normotensive patients and most of them had mild to moderate HT. We observed an increase in the prevalence of HT over the years in the cases that maintained active acromegaly. In our series only one of the three patients cured became normotensive, therefore, we concluded that HT in acromegaly is frequently irreversible. The chances of normalization seems higher in younger patients and probably with a shorter duration of acromegaly.

Characterization and regulation of glycine transport in Fusarium oxysporum var. lini

Glycine was transported in Fusarium oxysporum cells, grown on glycine as the sole source of carbon and nitrogen, by a facilitated diffusion transport system with a half-saturation constant (Ks) of 11 mM and a maximum velocity (Vmax) of 1.2 mM (g dry weight)-1 h-1 at pH 5.0 and 26 degrees C. Under conditions of nitrogen starvation, the same system was present together with a high-affinity one (Ks) of about 47 microM and Vmax of about 60 microM (g dry weight)-1 h-1). The low-affinity system was more specific than the high-affinity system. Cells grown on gelatine showed the same behavior. In cells grown on glucose-gelatine medium, the low-affinity system was poorly expressed even after carbon and nitrogen starvation. Moreover, addition of glucose to cells grown on glycine and resuspended in mineral medium caused an increase of the glycine transport probably due to a boost in protein synthesis. This stimulation did not affect the Ks of the low-affinity system. These results demonstrate that, as is the case for other eukaryotic systems, F. oxysporum glycine transport is under control of nitrogen sources but its regulation by carbon sources appears to be more complex.

[Beneficial effects of added glicazide in patients with type II diabetes mellitus treated with insulin]

The aim of the study was to assess, in patients with non insulin dependent diabetes mellitus (NIDDM), either with previous failure to sulphonylureas or insulin treated since the disease started, if the combination of gliclazide to insulin therapy might induce a reduction of daily insulin requirement. 30 caucasian type II patients used to self-monitoring (11 female, 19 male, mean age 55.78 +/- 8.07) with residual pancreatic function (glucagon induced C-peptide release = 1.01 +/- 0.70 microgram/ml) entered the study. 8 were excluded for non compliance or for high antiinsulin antibodies levels and 4 are still under study. Each patients was given, for 3 months, 240 mg of gliclazide in addition to usual daily dose of insulin. Data presented as mean +/- s.e.m. were analysed with analysis of variance (p less than 0.05). Mean initial values of main parameters were as follows: glycaemia 192.7 +/- 33.1 mg/100 ml, insulinaemia 9.5 +/- 4.5 microUI/ml, daily insulin requirements 33.11 +/- 10.47 U/d, HbA1 C 7.5 +/- 1.7%. Total cholesterol 240.1 +/- 52.2 mg/10 ml, triglycerides 120.6 +/- 60.3 mg/100 ml. After 3 months treatment significant reduction in mean daily insulin requirements (20.78 +/- 16.15 U/d) was observed. In 13 patients (72.2%) while keeping good metabolic control (HbA1 C 7.46 +/- 1.63), insulin therapy was reduced (9 patients) or even stopped (4 patients). In the other 5, insulin was maintained or slightly increased. The increase in glucagon induced C-peptide release (1.41 +/- 0.99 micrograms/ml) did not reach significance, while glycaemia and insulinaemia were not changed (196.0 +/- 34.1 mg/100 ml, 11.02 +/- 5.05 microUI/ml).(ABSTRACT TRUNCATED AT 250 WORDS)