Browse

You are looking at 1 - 3 of 3 items for :

  • Genetic analysis x
  • Paediatric endocrinology x
Clear All
Open access

Yang Timothy Du, Lynette Moore, Nicola K Poplawski and Sunita M C De Sousa

Summary

A 26-year-old man presented with a combination of permanent neonatal diabetes due to pancreatic aplasia, complex congenital heart disease, central hypogonadism and growth hormone deficiency, structural renal abnormalities with proteinuria, umbilical hernia, neurocognitive impairment and dysmorphic features. His older brother had diabetes mellitus due to pancreatic hypoplasia, complex congenital heart disease, hypospadias and umbilical hernia. Their father had an atrial septal defect, umbilical hernia and diabetes mellitus diagnosed incidentally in adulthood on employment screening. The proband’s paternal grandmother had a congenital heart defect. Genetic testing of the proband revealed a novel heterozygous missense variant (Chr18:g.19761441T>C, c.1330T>C, p.Cys444Arg) in exon 4 of GATA6, which is class 5 (pathogenic) using American College of Medical Genetics and Genomics guidelines and is likely to account for his multisystem disorder. The same variant was detected in his brother and father, but not his paternal grandmother. This novel variant of GATA6 likely occurred de novo in the father with autosomal dominant inheritance in the proband and his brother. The case is exceptional as very few families with monogenic diabetes due to GATA6 mutations have been reported to date and we describe a new link between GATA6 and renal pathology.

Learning points:

  • Monogenic diabetes should be suspected in patients presenting with syndromic features, multisystem congenital disease, neonatal-onset diabetes and/or a suggestive family history.

  • Recognition and identification of genetic diabetes may improve patient understanding and empowerment and allow for better tailored management.

  • Identification of a genetic disorder may have important implications for family planning.

Open access

Avinash Suryawanshi, Timothy Middleton and Kirtan Ganda

Summary

X-linked adrenoleukodystrophy (X-ALD) is a rare genetic condition caused by mutations in the ABCD1 gene that result in accumulation of very long chain fatty acids (VLCFAs) in various tissues. This leads to demyelination in the CNS and impaired steroidogenesis in the adrenal cortex and testes. A 57-year-old gentleman was referred for the assessment of bilateral gynaecomastia of 6 months duration. He had skin hyperpigmentation since 4 years of age and spastic paraparesis for the past 15 years. Physical examination findings included generalised hyperpigmentation (including skin, buccal mucosa and palmar creases), blood pressure of 90/60 mmHg, non-tender gynaecomastia and bilateral hypoplastic testes. Lower limb findings were those of a profoundly ataxic gait associated with significant paraparesis and sensory loss. Primary adrenal insufficiency was confirmed and investigations for gynaecomastia revealed normal testosterone with mildly elevated luteinising hormone level and normal prolactin. The combination of primary adrenal insufficiency (likely childhood onset), partial testicular failure (leading to gynaecomastia) and spastic paraparesis suggested X-ALD as a unifying diagnosis. A serum VLCFA panel was consistent with X-ALD. Subsequent genetic testing confirmed the diagnosis. Treatment with replacement doses of corticosteroid resulted in improvement in blood pressure and increased energy levels. We have reported the case of a 57-year-old man with a very late diagnosis of X-ALD manifested by childhood onset of primary adrenal insufficiency followed by paraparesis and primary hypogonadism in adulthood. Thus, X-ALD should be considered as a possibility in a patient with non-autoimmune primary adrenal insufficiency and neurological abnormalities.

Learning points

  • Adult patients with X-ALD may be misdiagnosed as having multiple sclerosis or idiopathic spastic paraparesis for many years before the correct diagnosis is identified.

  • Screening for X-ALD with a VLCFA panel should be strongly considered in male children with primary adrenal insufficiency and in male adults presenting with non-autoimmune primary adrenal insufficiency.

  • Confirmation of a genetic diagnosis of X-ALD can be very useful for a patient's family as genetic testing enables detection of pre-symptomatic female heterozygotes who can then be offered pre-natal testing to avoid transmission of the disease to male offsprings.

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.