Browse

You are looking at 1 - 7 of 7 items for :

  • Genetics and mutation x
Clear All
Open access

Sarah W Y Poon, Karen K Y Leung and Joanna Y L Tung

Summary

Severe hypertriglyceridemia is an endocrine emergency and is associated with acute pancreatitis and hyperviscosity syndrome. We describe an infant with lipoprotein lipase deficiency with severe hypertriglyceridemia who presented with acute pancreatitis. She was managed acutely with fasting and intravenous insulin infusion, followed by low-fat diet with no pharmacological agent. Subsequent follow-up until the age of 5 years showed satisfactory lipid profile and she has normal growth and development.

Learning points:

  • Hypertriglyceridemia-induced acute pancreatitis has significant morbidity and mortality, and prompt treatment is imperative.

  • When no secondary causes are readily identified, genetic evaluation should be pursued in hypertriglyceridemia in children.

  • Intravenous insulin is a safe and effective acute treatment for hypertriglyceridemia in children, even in infants.

  • Long-term management with dietary modifications alone could be effective for primary hypertriglyceridemia due to lipoprotein lipase deficiency, at least in early childhood phase.

Open access

Benjamin Kwan, Bernard Champion, Steven Boyages, Craig F Munns, Roderick Clifton-Bligh, Catherine Luxford and Bronwyn Crawford

Summary

Autosomal dominant hypocalcaemia type 1 (ADH1) is a rare familial disorder characterised by low serum calcium and low or inappropriately normal serum PTH. It is caused by activating CASR mutations, which produces a left-shift in the set point for extracellular calcium. We describe an Australian family with a novel heterozygous missense mutation in CASR causing ADH1. Mild neuromuscular symptoms (paraesthesia, carpopedal spasm) were present in most affected individuals and required treatment with calcium and calcitriol. Basal ganglia calcification was present in three out of four affected family members. This case highlights the importance of correctly identifying genetic causes of hypocalcaemia to allow for proper management and screening of family members.

Learning points:

  • ADH1 is a rare cause of hypoparathyroidism due to activating CASR mutations and is the mirror image of familial hypocalciuric hypercalcaemia.

  • In patients with ADH1, symptoms of hypocalcaemia may be mild or absent. Basal ganglia calcification may be present in over a third of patients.

  • CASR mutation analysis is required for diagnostic confirmation and to facilitate proper management, screening and genetic counselling of affected family members.

  • Treatment with calcium and activated vitamin D analogues should be reserved for symptomatic individuals due to the risk of exacerbating hypercalciuria and its associated complications.

Open access

C E Stiles, R Thuraisingham, D Bockenhauer, L Platts, A V Kumar and M Korbonits

Summary

29-year-old female presenting with an 8-year history of unexplained hypomagnesaemia, which was severe enough to warrant intermittent inpatient admission for intravenous magnesium. Urinary magnesium was inappropriately normal in the context of hypomagnesaemia indicating magnesium wasting. Ultrasound imaging demonstrated unilateral renal cysts and computed tomography of kidneys, ureters and bladder showed a bicornuate uterus. Referral to genetic services and subsequent testing revealed a de novo HNF1B deletion.

Learning points:

  • HNF1B loss-of-function mutations are one of the most common monogenic causes of congenital anomalies of the kidney and urinary tract.

  • Those with HNF1B mutations may have some of a constellation of features (renal and hepatic cysts, deranged liver function tests, maturity onset diabetes of the young type 5 (MODY5), bicornuate uterus, hyperparathyroidism, hyperuricaemic gout, but presenting features are highly heterogeneous amongst patients and no genotype/phenotype correlation exists.

  • HNF1B mutations are inherited in an autosomal dominant pattern but up to 50% of cases are de novo.

  • HNF1B mutations can be part of the Chr17q12 deletion syndrome, a contiguous gene deletion syndrome.

  • Inorganic oral magnesium replacements are generally poorly tolerated with side effects of diarrhoea. Organic magnesium compounds, such as magnesium aspartate, are better absorbed oral replacement therapies.

Open access

Nandini Shankara Narayana, Anne-Maree Kean, Lisa Ewans, Thomas Ohnesorg, Katie L Ayers, Geoff Watson, Arthur Vasilaras, Andrew H Sinclair, Stephen M Twigg and David J Handelsman

Summary

46,XX disorders of sexual development (DSDs) occur rarely and result from disruptions of the genetic pathways underlying gonadal development and differentiation. We present a case of a young phenotypic male with 46,XX SRY-negative ovotesticular DSD resulting from a duplication upstream of SOX9 presenting with a painful testicular mass resulting from ovulation into an ovotestis. We present a literature review of ovulation in phenotypic men and discuss the role of SRY and SOX9 in testicular development, including the role of SOX9 upstream enhancer region duplication in female-to-male sex reversal.

Learning points:

  • In mammals, the early gonad is bipotent and can differentiate into either a testis or an ovary. SRY is the master switch in testis determination, responsible for differentiation of the bipotent gonad into testis.

  • SRY activates SOX9 gene, SOX9 as a transcription factor is the second major gene involved in male sex determination. SOX9 drives the proliferation of Sertoli cells and activates AMH/MIS repressing the ovary. SOX9 is sufficient to induce testis formation and can substitute for SRY function.

  • Assessing karyotype and then determination of the presence or absence of Mullerian structures are necessary serial investigations in any case of DSD, except for mixed gonadal dysgenesis identified by karyotype alone.

  • Treatment is ideal in a multidisciplinary setting with considerations to genetic (implications to family and reproductive recurrence risk), psychological aspects (sensitive individualized counseling including patient gender identity and preference), endocrinological (hormone replacement), surgical (cosmetic, prophylactic gonadectomy) fertility preservation and reproductive opportunities and metabolic health (cardiovascular and bones).

Open access

Durgesh Prasad Chaudhary, Tshristi Rijal, Kunal Kishor Jha and Harpreet Saluja

Summary

Combined pituitary hormonal deficiency (CPHD) is a rare disease that results from mutations in genes coding for transcription factors that regulate the differentiation of pituitary cells. PROP1 gene mutations are one of the etiological diagnoses of congenital panhypopituitarism, however symptoms vary depending on phenotypic expression. We present a case of psychosis in a 36-year-old female with congenital panhypopituitarism who presented with paranoia, flat affect and ideas of reference without a delirious mental state, which resolved with hormone replacement and antipsychotics. Further evaluation revealed that she had a homozygous mutation of PROP1 gene. In summary, compliance with hormonal therapy for patients with hypopituitarism appears to be effective for the prevention and treatment of acute psychosis symptoms.

Learning points:

  • Patients with PROP1 gene mutation may present with psychosis with no impairment in orientation and memory.

  • There is currently inadequate literature on this topic, and further study on the possible mechanisms of psychosis as a result of endocrine disturbance is required.

  • Compliance with hormonal therapy for patients with hypopituitarism appears to be effective for prevention and treatment of acute psychosis symptoms.

Open access

Suresh Chandran, Fabian Yap Kok Peng, Victor Samuel Rajadurai, Yap Te Lu, Kenneth T E Chang, S E Flanagan, S Ellard and Khalid Hussain

Summary

background: Congenital hyperinsulinism (CHI) is a rare genetic disorder characterised by inappropriate insulin secretion in the face of severe hypoglycaemia. There are two histological subtypes of CHI namely diffuse and focal. Diffuse CHI is most common due to recessive mutations in ABCC8/KCNJ11 (which encode the SUR/KIR6.2 components of the pancreatic β-cell KATP channel) whereas focal CHI is due to a paternally inherited ABCC8/KCNJ11 mutation and somatic loss of heterozygosity for the 11p allele inside the focal lesion. Fluorine-18-l-dihydroxyphenylalanine positron emission tomography/computed tomography (18F-DOPA-PET/CT) is used in the pre-operative localisation of focal lesions prior to surgery. Diffuse CHI if medically unresponsive will require a near total pancreatectomy whereas focal CHI will only require a limited lesionectomy, thus curing the patient from the hypoglycaemia.

Aims: To report the first case of genetically confirmed CHI in Singapore from a heterozygous paternally inherited ABCC8 mutation.

Methods/Results: A term male infant presented with severe hyperinsulinaemic hypoglycaemia (HH) after birth and failed medical treatment with diazoxide and octreotide. Genetic testing (paternally inherited mutation in ABCC8/p.D1472N) suggested focal disease, but due to the unavailability of 18F-DOPA-PET/CT to confirm focal disease, a partial pancreatectomy was performed. Interestingly, histology of the resected pancreatic tissue showed changes typical of diffuse disease.

Conclusion: Heterozygous paternally inherited ABCC8/KCNJ11 mutations can lead to diffuse or focal CHI.

Learning points

  • HH is a cause of severe hypoglycaemia in the newborn period.

  • Paternal mutations in ABCC8/KCNJ11 can lead to diffuse or focal disease.

  • 18F-DOPA-PET/CT scan is the current imaging of choice for localising focal lesions.

  • Gallium-68 tetra-aza-cyclododecane-N NNN-‴-tetra-acetate octreotate PET scan is not a useful imaging tool for localising focal lesions.

  • The molecular mechanism by which a heterozygous ABCC8 mutation leads to diffuse disease is currently unclear.

  • Focal lesions are curable by lesionectomy and so genetic studies in patients with HH must be followed by imaging using 18F-DOPA-PET/CT scan.

Open access

R Casey, S Prendeville, C Joyce and D O'Halloran

Summary

We present the case of a 30-year-old female who was diagnosed with hereditary phaeochromocytoma secondary to a rare gene mutation in exon 8 of the RET oncogene. This genetic mutation was picked up as part of an extended genetic screen using a method known as next generation sequencing. Detection of this genetic mutation prompted further screening for the manifestation of multiple endocrine neoplasia type 2A (MEN2A). The patient subsequently underwent a thyroidectomy with histology confirming C-cell hyperplasia.

Learning points

  • Genetic analysis is an important step in the diagnostic work up of phaeochromocytoma.

  • Extended genetic analysis is important when there is a strong suspicion of hereditary phaeochromocytoma.

  • Mutations in exon 8 of the RET gene are associated with phaeochromocytoma as part of MEN2A syndrome.