Summary

A 20-year-old South Asian male presented with polyuria, polydipsia, HbA1c 81 mmol/mol, BMI 28.8 and family history of both type 1 and type 2 diabetes mellitus. As autoantibody testing was negative and c-peptide level demonstrated significant endogenous insulin secretion, type 1 diabetes was excluded. Given his age and family history, the differential diagnosis included maturity-onset diabetes of the young (MODY), a rare form of diabetes caused by a single-gene variant. A high probability of MODY was calculated and he was subsequently referred for genetic testing. Although a useful tool, the pre-test probability calculator for MODY is only validated in White Europeans. A heterogenous variant of unknown clinical significance of the NEUROD1 gene was detected, leading to gliclazide use with poor response. The patient responded well to metformin. Type 2 diabetes was considered the most likely diagnosis. This case highlights the diagnostic challenges in young patients of Asian ethnicity and the importance of interpreting genetic results of unknown significance within the clinical context. Ethnicity-specific BMI thresholds should be used when classifying patients as overweight or obese.

Learning points

• Variants of unknown significance detected by genetic sequencing should be interpreted within the context of the patient’s other clinical parameters.

• It is important to use ethnicity-specific BMI thresholds for obesity.

• Diagnosis of type 2 diabetes mellitus at younger ages is becoming increasingly common.

• The pre-test probability calculator for MODY is only validated in White Europeans; although a useful guide, results should be interpreted with caution in patients of other ethnicities.

Summary

A 73-year-old woman with type 2 diabetes mellitus was referred to our department for glycaemic control. Physical examination revealed two subcutaneous hard masses around the left shoulder and the right hip joint. The patient could not fully extend her fingers because of skin sclerosis in both hands. Laboratory studies showed hyperphosphataemia and a high ratio of renal tubular maximum reabsorption of phosphate to glomerular filtration rate. There were no abnormalities in serum calcium, creatinine, alkaline phosphatase, and intact parathyroid hormone levels, whereas serum fibroblast growth factor 23 was low. Hyperphosphataemic familial tumoural calcinosis/hyperostosis-hyperphosphataemia syndrome (HFTC/HHS) was diagnosed using whole genome sequencing that revealed a novel frameshift beyond the 584th threonine located in the lectin domain of UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3 associated with a duplication of the 1748th thymine in the coding region of the corresponding gene. Furthermore, anti-nuclear, anti-centromere, and anti-cardiolipin antibodies were positive, implying that comorbid limited type scleroderma might play a role in tumoural calcinosis (TC) development. A low phosphate diet was prescribed with phosphate-lowering medications, including aluminium hydroxide, acetazolamide, and sevelamer hydrochloride. The patient displayed a decrease in serum phosphate levels from 6.5 to 5.5 mg/dL 10 months after the initiation of treatment, but her TC had not improved during treatment for more than 1 year. This case was interesting because the patient with HFTC/HHS exhibited TC despite being over her 60s, and subsequent scleroderma might contribute to the specific clinical course. When HFTC/HHS presents with elderly-onset TC, the involvement of comorbidities in exacerbating TC should be considered.

Learning points

• HFTC/HHS occurs on an autosomal recessive basis, but its clinical course and manifestations differ significantly throughout the cases.

• HFTC/HHS may be undiagnosed until later in life because of its rarity, unfamiliarity, and phenotype diversity; therefore, HFTC/HHS should be included in the differential diagnosis of elderly patients with unexplained hyperphosphataemia or ectopic calcinosis.

• Comorbidities, including rheumatologic disorders, may contribute to developing HFTC/HHS-associated calcinosis.

Summary

We report a 61-year-old male patient without personal history of thyroid carcinoma or radiation exposure. In 2011, he presented with a cervical mass whose biopsy diagnosed a papillary thyroid carcinoma (PTC) in a lymph node metastasis (LNM). Total thyroidectomy with lymphadenectomy of central and ipsilateral compartment was performed. Histopathology identified a 2 mm follicular variant of PTC and LNM in 25/25 lymph nodes. The patient was treated with 150 mCi of radioactive iodine (RAI), followed by levothyroxine suppressive therapy. In 2016, a retrotracheal mass was diagnosed, suggesting local recurrence; patient was submitted to surgical excision and RAI therapy (120 mCi). Due to seizures, in 2019, a brain CT was performed that diagnosed brain metastases. The patient underwent debulking of the main lesion. Histopathology analysis confirmed a metastatic lesion with variated morphology: classical PTC and follicular pattern and hobnail and tall cell features. Molecular analysis revealed BRAFV600E in LNM at presentation and BRAFV600E and TERT promoter (TERTp) mutations in the recurrent LNM and brain metastasis. Based upon this experience we review the reported cases of subcentimetric PTC with brain metastases and discuss the molecular progression of the present case.

Learning points

• Papillary microcarcinoma (PMCs) usually have very good prognosis with low impact on patient survival.

• PMCs presenting in elderly patients with LNM at diagnosis may carry a guarded outcome.

• Brain metastasis although rare indicate aggressive phenotypic features.

• Patient risk stratification of PMCs based on histopathological analysis and genetic testing may have a significant impact on prognosis providing therapeutic markers, that may predict disease progression and overall outcome.

Summary

Neonatal hypoglycemia is a serious condition that can have a major impact on the growing neonatal brain. The differential diagnosis of neonatal hypoglycemia is broad and includes hyperinsulinism as well as panhypopituitarism. The FOXA2 gene has been involved in the development of the pancreas as well as the pituitary gland. Six cases have been reported thus far with FOXA2 mutations presenting with variable degrees of hypopituitarism, and only two patients had permanent hyperinsulinism; other cases have been reported with microdeletions in 20p11, the location that encompasses FOXA2, and those patients presented with a wider phenotype. A full-term female infant presented with severe hypoglycemia. Critical sampling showed an insulin of 1 mIU/mL, suppressed beta-hydroxybutyric acids, and suppressed free fatty acids. Blood glucose responded to glucagon administration. Growth hormone (GH) stimulation test later showed undetectable GH in all samples, and cortisol failed to respond appropriately to stimulation. Gonadotropins were undetectable at 1 month of life, and MRI showed ectopic posterior pituitary, interrupted stalk, hypoplastic anterior pituitary, cavum septum pellucidum, and diminutive appearance of optic nerves. Whole-exome sequencing revealed a likely pathogenic de novo c.604 T>C, p.Tyr202His FOXA2 mutation. We expand the known phenotype on FOXA2 mutations and report a likely pathogenic, novel mutation associated with hyperinsulinism and panhypopituitarism.

Learning points

• FOXA2 has been shown to play an important role in the neuroectodermal and endodermal development.

• FOXA2 mutation may lead to the rare combination of hyperinsulinism and panhypopituitarism.

• Patients reported so far all responded well to diazoxide. Dysmorphology may be subtle, and liver functions should be monitored.

Summary

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) lyase deficiency is an inborn error of metabolism resulting in a lack of ketogenesis and leucine catabolism. Hallmarks of decompensation include hypoglycemia without ketosis (or hypoketosis), metabolic acidosis, and hyperammonemia. Management includes avoiding fasting and restricting dietary protein and fat. Conversely, type 2 diabetes mellitus (T2DM) requires carbohydrate restriction and/or anti-hyperglycemic agents; thus, managing these co-existing disorders is challenging. A 36-year-old male with HMG-CoA lyase deficiency and T2DM (Hemoglobin A1c (HbA1c): 7.9%) presented with confusion and shock. Blood work revealed metabolic acidosis, hyperammonemia, hyperglycemia, and hypoketosis. The patient was diagnosed with hyperosmolar non-ketotic hyperglycemia and hyperammonemia secondary to HMG-CoA lyase metabolic decompensation requiring intensive care unit admission. Hyperammonemia management was challenging because alternative calories with i.v. dextrose (due to hyperglycemia) and i.v. lipids (due to HMG-CoA lyase deficiency) could not be provided as usual. The patient was started on hemodialysis and i.v. insulin with marked improvement. Once stabilized, metformin and insulin were initiated. T2DM impaired cellular glucose uptake and produced a state similar to hypoglycemia, despite the patient being profoundly hyperglycemic, which led to metabolic decompensation of HMG-CoA lyase deficiency. Managing T2DM and HMG-CoA lyase deficiency warrants special considerations due to the potential for metabolic decompensation with both hyperglycemia and hypoglycemia.

Learning points

• In a patient with 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) lyase deficiency and type 2 diabetes mellitus (T2DM), management principles include avoiding hypoglycemia to prevent metabolic decompensation, providing insulin for proper glucose utilization, and moderation of carbohydrate intake to prevent consequences of chronic hyperglycemia.

• The development of insulin resistance in the form of T2DM in HMG-CoA lyase deficiency likely triggered a state similar to hypoglycemia, leading to cellular energy deficiency and subsequently metabolic decompensation.

• It is important to avoid hypoglycemia in patients with HMG-CoA lyase deficiency and T2DM, as the risk of metabolic decompensation is increased due to the lack of ketogenesis in HMG-CoA lyase deficiency.

• Selection of antidiabetic agents in this patient population requires careful consideration, and agents that have a higher risk of hypoglycemia should be avoided.

Summary

A male phenotype accompanied by a 45,X karyotype is rare. It may occur due to Y chromosomal translocation or insertion to X/autosome. Clinical presentation may vary depending on the presence of the Y chromosomal locus and the degree of loss of autosome material. 45,X males can present with short stature and Turner syndrome phenotype due to haploinsufficiency of genes which are normally expressed in both X and Y chromosomes. The presence of the sex-determining region Y (SRY) gene leads to the differentiation of bipotential gonads to testis. Most individuals go through puberty normally, but some may need pubertal induction for delayed puberty. Rarely some can have a pubertal arrest. The risk of gonadoblastoma is minimal in these individuals due to functioning testicular tissue. The azoospermia factor (AZF) region is found on the long arm of the Yq chromosome and is needed for spermatogenesis. In a 45,X male with unbalanced translocation of Y chromosome, spermatogenesis can be affected due to the lack of AZF leading to Sertoli cell-only syndrome. This will have an implication on fertility in adult life. We present a 14-year-old boy with developmental delay, learning difficulties and subtle dysmorphic features who was diagnosed with 45,X,der(2)t(Y:2)(?:p25). Fluorescence in situ hybridisation analysis revealed translocation of SRY (Yp11.3) to the terminal part of the short arm of chromosome 2 resulting in the deletion of most of the Y chromosome (Yp11.2-q12) and part of chromosome 2(2p25.3). This is the first case where SRY translocation to chromosome 2 presents with the above clinical presentation.

Learning points

• 45,X karyotype is rare in male.

• It may occur due to SRY translocation or an insertion to X/autosome.

• SRY gene translocation to chromosome 2 has been not reported in the literature.

• Clinical presentation can be varied due to degree of loss of chromosomal material.

• Due to loss of AZF region found on the long arm of the Yq, spermatogenesis can be affected. Loss of 2p25 leads to learning difficulty and obesity.

Summary

The most frequent causes of pancreatitis classically have been known to be gallstones or alcohol. However, genetics can also play a key role in predisposing patients to both chronic and acute pancreatitis. The serine protease inhibitor Kazal type 1 (SPINK 1) gene is known to be strongly associated with pancreatitis. Patients with these underlying genetic mutations can have severe diseases with a high morbidity rate and frequent hospitalization. We report an Arab girl who presented with acute pancreatitis at the age of 7 years progressing to recurrent chronic pancreatitis over a few years. She had severe obesity from the age of 4 years and developed type 2 diabetes at the age of 12. She had a normal biliary system anatomy. Genetic analysis showed that she had combined heterozygous mutations in the SPINK1 gene (SPINK1, c.101A>G p.(Asn34Ser) and SPINK1, c.56-37T>C). Her parents were first-degree cousins, but neither had obesity. Mother was detected to have the same mutations. She had type 2 diabetes but never presented with pancreatitis. This case is the first to be reported from the Arab region with these combined mutations leading to recurrent chronic pancreatitis. It illustrates the importance of diagnosing the underlying genetic mutation in the absence of other known causes of pancreatitis. Considering the absence of pancreatitis history in the mother who did not have obesity but harboured the same mutations, we point out that severe obesity might be a triggering factor of pancreatitis in the presence of the mutations in SPINK1 gene in this child. While this is not an assumption from a single patient, we show that not all carriers of this mutation develop the disease even within the same family. Triggering factors like severe obesity might have a role in developing the disease.

Learning points

• Acute recurrent pancreatitis and chronic pancreatitis are uncommon in children but might be underdiagnosed.

• Biliary tract anomalies and dyslipidaemias are known causative factors for pancreatitis, but pancreatitis can be seen in children with intact biliary system.

• Genetic diagnosis should be sought in children with pancreatitis in the absence of known underlying predisposing factors.

• SPINK1 mutations can predispose to an early-onset severe recurrent pancreatitis and acute pancreatitis.

Summary

A paired homeodomain transcription factor, PAX6 (paired-box 6), is essential for the development and differentiation of pancreatic endocrine cells as well as ocular cells. Despite the impairment of insulin secretion observed in PAX6-deficient mice, evidence implicating causal association between PAX6 gene mutations and monogenic forms of human diabetes is limited. We herein describe a 33-year-old Japanese woman with congenital aniridia who was referred to our hospital because of her uncontrolled diabetes with elevated hemoglobin A1c (13.1%) and blood glucose (32.5 mmol/L) levels. Our biochemical analysis revealed that her insulin secretory capacity was modestly impaired as represented by decreased 24-h urinary C-peptide levels (38.0 μg/day), primarily explaining her diabetes. Intriguingly, there was a trend toward a reduction in her serum glucagon levels as well. Based on the well-recognized association of PAX6 gene mutations with congenital aniridia, we screened the whole PAX6 coding sequence, leading to an identification of a heterozygous Gln135* mutation. We tested our idea that this mutation may at least in part explain the impaired insulin secretion observed in this patient. In cultured pancreatic β-cells, exogenous expression of the PAX6 Gln135* mutant produced a truncated protein that lacked the transcriptional activity to induce insulin gene expression. Our observation together with preceding reports support the recent attempt to include PAX6 in the growing list of genes causally responsible for monogenic diabetes. In addition, since most cases of congenital aniridia carry PAX6 mutations, we may need to pay more attention to blood glucose levels in these patients.

Learning points

• PAX6 Gln135* mutation may be causally associated not only with congenital aniridia but also with diabetes.

• Blood glucose levels may deserve more attention in cases of congenital aniridia with PAX6 mutations.

• Our case supports the recent attempt to include PAX6 in the list of MODY genes, and Gln135* may be pathogenic.

Summary

The coexistence of neurofibromatosis type 1 (NFT1) and Turner syndrome (TS) has only been reported in a few patients and may represent a diagnostic challenge. We describe the case of a 16-year-old girl, with a prior clinical diagnosis of NFT1, who was referred to Endocrinology appointments for the etiological study of primary amenorrhea. Evaluation of the anterior pituitary function was requested and hypergonadotropic hypogonadism was detected. During the etiological study, a 45X karyotype was found and TS was diagnosed. The fact that NFT1 can also be associated with short stature, short broad neck and hypertelorism was likely responsible for TS being diagnosed in late adolescence. As both TS and NFT1 are relatively common genetic disorders, it is important to be alert to the possibility that the presence of one disease does not invalidate the other.

Learning points

• The concomitant presence of two syndromes in the same patient is unlikely and represents a diagnostic challenge.

• Some phenotypic characteristics and clinical manifestations may be shared by several syndromes.

• Some syndromes, such as neurofibromatosis type 1 may have very heterogeneous presentations.

• It is important to be alert to the characteristics that are not explained by the initial diagnosis.

• If such features are present, diagnostic work-up must be performed regardless of the initial syndromic diagnosis.

Summary

The coexistence of autoimmune diabetes and maturity-onset diabetes (MODY) is rare. The absence of pancreatic autoantibodies is a key factor prompting MODY genetic testing. In this study, we report three cases of young-onset diabetes with progressive beta-cell dysfunction, strongly positive glutamic acid decarboxylase (GAD) antibodies, and genetic confirmation of pathogenic gene variants of HNF-1A, HNF-4A, and ABCC8-MODY. The first case is a woman diagnosed with HNF-1A-MODY diabetes more than 30 years after her diagnosis of adult-onset diabetes at 25 years. She required insulin after her fourth pregnancy. She became ketotic on oral hypoglycaemic agents (OHAs) and subsequently, her GAD antibodies tested positive. The second case is a woman diagnosed with diabetes at 17 years who was subsequently diagnosed with HNF-4A-MODY after many hypoglycaemic episodes on low-dose insulin. GAD antibodies were strongly positive. The last case is a man diagnosed with diabetes at 26 years who was well controlled on OHAs and required insulin years later due to sudden deterioration in glycaemic control. His ABCC8-MODY was diagnosed upon realisation of strong family history and his GAD antibodies tested positive. All subjects are now treated with insulin. Less than 1% of subjects with MODY have positive autoantibodies. These cases highlight individuals who may have two different types of diabetes simultaneously or consecutively. Deterioration of glycaemic control in subjects with MODY diabetes should highlight the need to look for the emergence of autoantibodies. At each clinic visit, one should update the family history as MODY was diagnosed in each case after the development of diabetes in their offspring.

Learning points

• These cases highlight the rare coexistence of autoimmune diabetes and MODY.

• Deterioration of glycaemic control in subjects with MODY diabetes should highlight the emergence of autoantibodies.

• One should revise and update the family history as the diagnosis of MODY was made after the development of diabetes in offspring.

• Understanding the spectrum of diabetes allows for precision medicine.