Inherited endocrine syndromes
This is a family of endocrine
neoplasia syndromes that are inherited in an autosomal dominant manner:
· multiple endocrine neoplasia (MEN)
type 1;
· MEN type 2;
· Von Hippel–Lindau (VHL) syndrome.
The molecular genetic defects for
these syndromes have been identified and genetic screening is available.
Patients with these conditions require close surveillance and screening
(biochemistry, radiology, etc.).
The condition is characterized by
the following clinical features.
· Hyperparathyroidism (90%). Due to
parathyroid hyperplasia. Usually presents in second decade of life.
· Pancreatic endocrine tumours
(75%). Typically multifocal, pancreatic islet cell tumours. Include insulinoma
(60%); gastrinoma (30%); VIPoma (rare); glucagonoma (rare). Present in
adulthood.
· Pituitary adenomas (10–65%).
Prolactinoma (60%); GH-secreting (30%).
· Other features: thyroid adenoma;
thymic/bronchial carcinoid tumours; lipomas.
MEN type 2 belongs to a family of
three syndromes (MEN type 2A; MEN type 2B; familial medullary thyroid cancer)
characterized by activating mu-tations in the RET proto-oncogene. Medullary thyroid cancer is a common feature in
all the syndromes.
· Medullary thyroid cancer (90%).
· Phaeochromocytoma (50%).
· Parathyroid ademona (25%).
· Medullary thyroid cancer (90%).
· Phaeochromocytoma.
· Mucosal/intestinal
ganglioneuromas.
· Marfanoid body habitus.
· Hirschsprung’s disease.
Isolated medullary thyroid cancer.
This condition is due to a
mutation in the VHL gene. This is a
tumour re-pressor gene that is located on chromosome 3.
The condition is characterized by
the following features:
· Retinal
haemangioblastomas (40%):
· Uncommon before age 10yrs.
Bleeding and retinal detachment.
·CNS
haemangioblastomas: 75%
occur in cerebellum.
·Phaeochromocytomas
(20%): bilateral in 40%.
·Renal
cysts and carcinomas:
· Late feature: from 4th decade.
· Occur in 70% by age 60yrs.
·Pancreatic
neuroendocrine tumours: uncommon.
50% malignant. Most are
non-functioning tumours, but may be secreting (insulin, glucagons, VIP).
·Simple
adenomas/cysts: uncommon.
· Pancreas; liver; epididymis; lung.
· Meningioma.
Characterized by the following
triad of clinical features:
·Skin:
hyperpigmented (café au lait) macules.
· classically, irregular edge
(so-called ‘coast of Maine’ appearance);
· do not cross midline.
·Polyostic
fibrous dysplasia:
· slowly progressive bone lesion;
· any bones, although facial/base of
skull bones most commonly affected.
·Autonomous
endocrine gland hyperfunction:
· ovary most commonly affected;
· precocious puberty
(gonadotrophin-indepdent);
· thyroid (hyperthyroidism);
· adrenal (Cushing’s syndrome);
· pituitary (adenoma—gigantism);
· parathyroid (hyperparathyroidism).
Two types of neurofibromatosis
(NF) are recognized. Type 1 (NF-1; also known as von Recklinghausen’s disease)
is an autosomal dominant condition due to a mutation of the NF-1 gene.
NF-1 may be associated with
endocrine abnormalities:
·Hypothalamic/pituitary tumours:
optic glioma (15%).
·GH deficiency.
·Precocious puberty.
Delayed puberty.
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