Molecular genetics in familial primary hyperparathyroidism: A study from Northern India

doi:10.21203/rs.3.rs-5299691/v1

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Molecular genetics in familial primary hyperparathyroidism: A study from Northern India

https://doi.org/10.21203/rs.3.rs-5299691/v1

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Purpose

Familial primary hyperparathyroidism (FPHPT) accounts for about 10% of cases, owing to germline mutations in specific genes. The genetic profile of FPHPT has not been studied in our population. This is most likely the first study in our region to examine the genetic profile to search for any other PHPT-related tumours in these patients.

Methods

This prospective cross-sectional study was conducted in the Department of Endocrinology SKIMS from February 2021 to February 2023, in which 103 patients diagnosed with PHPT were taken. A customised gene panel (CDC 73, MEN 1/2A/4 mutation) using next-generation sequencing (NGS)was performed in 39 patients with strong suspicious of FPHT based on age < 35 years, multiglandular disease, cystic parathyroid adenoma (PA), parathyroid carcinoma (PC), suspicious of MEN 1/2A/4 syndrome. We tried to compare the clinical characteristics of individuals with those of positive and negative genetic tests.

Results

Germline variants were observed in 11/39 (28.2%). 7(17.9%) patients tested positive for MEN 1 mutation while 4(10.2%) patients tested positive for CDC 73 mutation; however, no one tested positive for MEN 2A/4 mutation. 4 patients with MENI syndrome had c.1366-2A > G p? while as 1 had c.247_250del CTGT(p.Ile85SerfsTer33), 1 had c.1763C > T (p.S588L), 1 had c.415 C > T(p.H139Y). Out of 7 who tested positive for MEN 1 mutation, 2 patients had microprolactinomas, 2 had multi-glandular disease, 1 had recurrent disease, 1 had persistent disease, 1 had gastric neuroendocrine tumour. In contrast, out of 4 who tested positive for CDC 73 mutation, 2 had familial PHPT, 1 had multiple uterine fibroids, and 1 had bilateral renal cysts. In the case of patients with CDC 73 mutations, 1 patient had codon 222 CGA (Arg) > TGA, 1 had c.415C > T at codon 139 (R139X), 1 had c.687_688dellAG (p.Arg229Serfs37), other had c76delA (p.Ile26SerfsX11). These were all reported mutations. Age, greater serum calcium, higher ALP and more skeletal involvement were statistically significant characteristics of those who tested positive for the mutation.

Conclusion

The observed prevalence of genetic variants in our population was remarkably higher than in other populations. Recognition of predisposing germline mutations can have significant implications in patient management, such as preventing PC in HPT-JT and optimizing the approach to parathyroidectomy in MEN 1. So, we strongly recommend genetic screening in PHPT patients with high-risk features.

Familial PHPT

CDC 73

Molecular genetics

MEN 1

Next generation sequencing

Primary hyperparathyroidism (PHPT) is a disease characterised by hypercalcemia due to the autonomous production of parathyroid hormone (PTH), which results from excessive secretion from one or more parathyroid glands. PHPT is the third most common endocrine disorder in the West after diabetes mellitus and thyroid disorders [1]. Overall, about 1% of adults have PHPT in the West, and this figure rises to 2% in people older than 55 years [2]. PHPT in India, for the most part, continues to be a symptomatic disease with skeletal, renal, pancreatic and cardiac manifestations with high serum calcium and PTH levels [3, 4, 5].

Sporadic PHPT cases represent about 90–95% of all cases, resulting from single parathyroid adenoma in 80% of cases and multiple gland involvement, which is generally hyperplasic in 20% [6]. The remaining 5–10% of all PHPT cases are due to pathogenic germline variants in genes [7, 8], a condition known as familial primary hyperparathyroidism (FHPT) [9]. This prevalence increases to 15–26% in patients with high-risk features suggestive of FHPT [10]. However, there is general agreement that FHPT is underdiagnosed and underreported in the literature, likely due to the limited number of genetic studies performed in routine clinical practice, unavailable family history, variable penetrance and an insufficient understanding of the genetics of PHPT. FHPT may occur either as an isolated clinical disorder or as part of a syndrome, such as multiple endocrine neoplasia (MEN) types 1, 2A, and 4, and hyperparathyroidism-jaw tumour syndrome (HPT-jaw tumour) [CDC 73] syndrome. MEN1 is caused by inactivating germline variants of the MEN1 tumour suppressor gene that produce PHPT, gastroenteropancreatic neuroendocrine tumours, pituitary adenomas, and other tumours, such as carcinoids or lipomas [11]. MEN2A is caused by activating variants in the proto-oncogene RET and typically presents as medullary thyroid carcinoma, pheochromocytoma, and parathyroid tumours (20–30%) with a lower penetrance [12]. HPT-jaw tumour syndrome is caused by germline inactivating variants of the CDC73 (HRPT2) tumour suppressor gene. These mutations can result in PHPT, fibro-osseous jaw tumours, and renal and uterine tumours [13, 14]. Other forms of FHPT include familial hypocalciuric hypercalcemia syndrome (FHH), neonatal severe hyperparathyroidism (NSHPT), and familial isolated PHPT (FIPH) [15]. FIHP is diagnosed by exclusion because the genetic cause is unknown in most cases [16–18]. Current guidelines [19, 20, 21] recommend genetic analysis in individuals younger than 35 years of age, multiglandular disease, family history of PHPT, parathyroid carcinoma (PC), cystic parathyroid adenoma (PA), patients with a strong suspicious of MEN1/MEN2A/MEN 4 syndrome and CDC 73 related disorder. Genetic testing is of considerable interest to patients with PHPT of a presumed familial origin for several reasons. This makes it possible to ascertain which patients are most likely to develop other neoplasms (e.g. in MEN and HPT-jaw tumour syndromes) and organise the best management for every PHPT patient. Genetic testing also allows surveillance for other clinical features associated with a given genetic disorder and testing asymptomatic relatives, which enables early detection of potentially serious illnesses and reduces healthcare burden and psychological stress in mutation-negative relatives. Lastly, if needed, it offers prenatal diagnosis and appropriate genetic counselling [22, 23, 10, 13]. There are limited studies on molecular genetics in PHPT, mainly from the Western world. To the best of our knowledge, there are no studies from developing regions like India. Besides, previous studies on molecular genetics in PHPT have used Sanger sequencing; our study used next-generation sequencing.

Inclusion criteria

Out of 103 patients with PHPT evaluated in the Department of Endocrinology at our university hospital over two years (February 2021 to February 2023), 39 patients met the criteria for genetic analysis based on one or more of the following characteristics:

HPT- JT (Hyperparathyroidism jaw tumour) features include ossifying fibromas of the mandible and/or maxilla, uterine tumours (e.g., adenofibromas, leiomyomas, adenomyosis, hyperplasia, adenosarcomas) and malignant and non-malignant renal lesions (Wilms tumour, clear cell renal carcinoma, papillary renal cell tumour, renal cysts).

Family history of PHPT

Parathyroid cancer (PC)

Patient age less than 35 years.

Cystic Parathyroid adenoma (PA)

Multiglandular disease.

Patients with a strong suspicion of MEN 1/MEN 2A, 4 syndromes.

Biochemical evaluation

An automated chemistry analyser analysed fasting serum samples for calcium, phosphate, creatinine and alkaline phosphatase (ALP). A 24-hour urine collection was analysed for calcium and creatinine. The normal laboratory range is 8.5–10.5 mg/dl for serum calcium and 2.5–4.5 mg/dl for serum phosphate. Serum iPTH and 25-hydroxy vitamin D (25-OHD) were measured by DXI 800, Beckman Coulter Chemiluminescence random access analyzer (Brea, CA), following the manufacturer’s protocol. The reference range for PTH levels is 12–88 pg/ml. The intra-assay and inter-assay coefficients of variation of the iPTH assay were 2.1% and 3.9%, respectively, and that of the 25-OHD assay were 3.6% and 6.5%, respectively.

Radiological evaluation

A radiological survey of the hands, skull, lumbar spine, pelvis, and any other suspected or known fracture site was performed. Three-site bone mineral density (BMD), including the lumbar spine, dual femur, and distal radius, was measured with the help of lunar Dual Energy X-ray Absorptiometry (DXA). Patients were reported as having osteopenia or osteoporosis or normal, according to WHO [24].Renal ultrasonography (USG) was performed to diagnose renal stones, nephrocalcinosis, or renal cysts. Parathyroid adenoma was localised by USG neck, technetium-99m (^99m Tc) sestamibi scan, and, in cases with negative or discordant USG and ^99mTc, 4D-computerised tomography (CT) neck. Female patients underwent pelvic USG for any uterine tumours.

Genetic analysis

From the patients chosen for genetic analysis, 5ml of peripheral blood from a peripheral vein was collected in EDTA vials and stored at − 80 ° C. Genomic DNA was isolated from blood samples by phenol-chloroform method/ DNA extraction Kits. DNA quality and the content were checked by Agarose gel electrophoresis and spectrophotometry, respectively. Primers were designed for the whole gene (exons 1–17) of the CDH1 gene by primer designing software. Polymerase chain reaction (PCR) was performed using Thermal Cycler to amplify the desired targets. A customized NGS panel was used for target sequencing of CDC 73, MEN1 and, MEN 2A, MEN 4 genes. The nucleic acid (DNA) received was quality-checked. Briefly, 10ng of DNA was amplified using a custom thermo assay designed by the client (covering 3 genes and having 14,626 bp in the target region) as per the instruction manual, and sequencing was performed using the Ion S5 platform as per the user manual. The sequencing reads QC, mapping on hg19 human reference genome, variant calling (SNVs, small InDels, CNVs) and annotation was carried out with IonReporter™ (IR) Software 5.18.2.0. Later, the RefSeq database was used to identify and characterise genes-associated variants. The annotation for variants was derived using various disease databases like OMIM and ClinVar. The population frequency information from 1000 genomes, ExAC, GnomAD, dbSNP and ESP, was used to eliminate common variants/polymorphism. For the prediction of the possible impact of coding variants on the structure and function of a protein, PolyPhen-2 and SIFT scores were used. Also, all variants were separately analysed by multiple other prediction tools for in-silicon variant effect prediction. All variants were then interpreted based on ACMG guidelines [25] and reported.

Objectives of the study

Determine the prevalence of germline mutations in the analysed genes in selected patients with PHPT.
Compare the prevalence of germline variants in our population with those in other cohorts
Compare biochemical parameters and end-organ complications (renal and/or skeletal disease) in those with a positive and negative genetic test.

Definitions

PHPT: PHPT was defined as persistent hypercalcemia and concomitantly raised or inappropriately normal serum intact PTH (i PTH).
FHPT: FHPT was defined as PHPT with one or more characteristics listed in the inclusion criteria.
Renal disease was defined as ultrasonographic evidence of renal stones and/or nephrocalcinosis.
Skeletal disease: Skeletal disease was defined as X-ray evidence of subperiosteal resorption, fractures, a salt-and-pepper appearance of the skull or brown tumour, and/or DXA evidence of osteopenia or osteoporosis.
Multiglandular disease: Multiglandular disease was defined as a biopsy documented involvement of 2 or more glands affected by either adenomas or hyperplasia.
Persistent PHPT: Persistent PHPT was defined as hypercalcemia and raised iPTH at any time during the six-month period after parathyroid surgery.
Recurrent PHPT: Recurrent PHPT was defined as hypercalcemia and raised iPTH following a period of normocalcemia for six months or longer after parathyroid surgery.

Statistical analysis

The recorded data was compiled and entered in a spreadsheet (Microsoft Excel) and then exported to the data editor of SPSS Version 20.0 (SPSS Inc., Chicago, Illinois, USA). Continuous variables were expressed as Mean±SD, and categorical variables were summarised as frequencies and percentages. Students' independent t-test or Mann-Whitney U-test, whichever is feasible, was employed to compare continuous variables. The chi-square test or Fisher’s exact test, whichever is appropriate, was applied to compare categorical variables. A P-value of less than 0.05 was considered statistically significant.

Treatment

All participants with germline variants in MEN 1 were subjected to subtotal parathyroidectomy, while patients who tested positive for germline variants in CDC 73 were subjected to single gland excision.

The clinical and laboratory characteristics of the 39 patients are shown in Table 1. The majority of patients were females, 79.5%. The mean age of our patients was 31.68 ± 10.35 (12–60) years. Renal and skeletal disease were present in 66.7% and 38.4% of patients, respectively. Genetic sequencing of the targeted gene panel identified pathogenic germline variants in 11 of the 39 patients (28.2%). Seven (17.9%) patients tested positive for germline variants in MEN 1, while 4 (10.2%) patients tested positive for germline variants in CDC 73. No patient tested positive for germline variants in MEN 2A and MEN 4. The clinical and laboratory characteristics of patients with pathogenic germline variants are shown in Table 2, and the genetic profile is shown in Table 3. Four out of seven patients with germline variants in MEN 1 carried splice variant c.1366-2A > G p?. These four patients were unrelated. One patient carried missense variant c.1763C > T (p.S588L), one patient carried frameshift variant c.247_250del CTGT (p.Ile85SerfsTe r33) and one patient carried missense variant c.415 C > T (p.H139Y). All these germline variants have been previously reported as pathogenic. Two of the 7 patients with MEN 1 germline variants had microprolactinomas, and one had pancreatic neuroendocrine endocrine. All seven patients had multi-glandular disease at surgery and were subjected to sub-total parathyroidectomy. Five patients were cured, while one patient had a persistent disease, and one had a recurrence. Out of four patients with germline variants in CDC 73, one carried c. 222 CGA (Arg) > TGA, one carried c.415C > T at codon 139 (R139X), one carried c.687_688dellAG, p.(Arg229Serfs37) and one carried c76delA p.Ile26SerfsX11. Three patients had a missense mutation, and one had a stop codon. All these variants have been previously reported as pathogenic variants. Two participants with germline variants in CDC 73 had features of HPT- JT (one had multiple uterine fibroids, and one had bilateral renal cysts); none had ossifying fibromas of the jaw. Two patients had a family history of PHPT. All four patients had uniglandular presentation surgery and were subjected to single gland excision and achieved cure. Table 4 shows the difference between the characteristics of patients with positive and negative genetic tests. Those with germline variants were younger than those without germline variants (median 25 vs 30.5 years, p 0.029) and had significantly higher serum calcium and ALP (median serum calcium 12.9 vs 12 mg/dl, p 0.045; median ALP 332 vs 134 IU/l, p 0.004). Patients with germline variants had significantly higher 24-hour urinary calcium than those without germline variants (median 600 vs 414, p 0.029). Skeletal disease was more common in patients with germline variants (63.63% vs 28.57%, p 0.043). There was no difference in renal disease between the two groups. Multiglandular disease was also more common in patients with germline variants, but this was not statistically significant.

Table 1

Clinical and laboratory characteristics of patients (n = 39).
Age (year)	31.68 ± 10.35^*
Gender	n (%)
Male	8 (20.5)
Female	31 (79.5)
Clinical features	n (%)
Polydipsia and /or polyuria	17 (43.5)
Bone pains	22 (57.3)
Constipation	11 (31.1)
Abdominal pain	12(32)
Cholelithiasis	9 (23.1)
Pancreatitis	3 (7.6)
Apathy	9 (23.1)
Depression	4 (10.2)
Renal disease	26 (66.7)
Skeletal disease	15 (38.4)
Biochemical features	Median (range)
Serum calcium(mg/dl)	12.45 (10.5–14.8)
Serum phosphate (mg/dl)	2.25 (1.08–3.66)
ALP (IU/L)	233 (86-4135)
iPTH (pg/ml)	211.5 (89-1900)
24 hr Urinary calcium (mg/day)	507.25 (167–1135)
ALP alkaline phosphatase, iPTH intact parathyroid hormone
*Mean ± standard deviation

Table 2

Clinical and laboratory characteristics of patients with pathogenic germline variants (n = 11).
Patient	Age/Sex	Serum calcium (mg/dl)	Serum phosphate (mg/dl)	ALP (IU/L)	iPTH (pg/ml)	Parathyroid pathology	Associated disease/features
Case 1	30/F	12.07	2.1	374	250	Multiglandular disease	Microprolactinoma
Case 2	28/F	13.6	2.39	217	173	Multiglandular disease	Microprolactinoma
Case 3	35/F	14	2.64	564	1229	Multiglandular disease	Recurrent PHPT
Case 4	23/F	11.41	1.59	283	347	Multiglandular disease	Persistent PHPT
Case 5	32/F	12.6	2.2	432	226	Multiglandular disease	Nil
Case 6	25/F	11.7	2.3	167	107	Multiglandular disease	Pancreatic neuroendocrine tumour
Case 7	31/F	13.6	2.2	332	332	Multiglandular disease	Nil
Case 8	12/F	14.8	3.18	4135	1900	Single adenoma	Family history of PHPT
Case 9	22/F	12.9	3.6	483	475	Single adenoma	Multiple Uterine fibroids
Case 10	25/M	11.1	3.42	141	248	Single adenoma	Family history of PHPT
Case 11	21/M	12.9	2.1	97	129	Single adenoma	Bilateral renal cysts
ALP alkaline phosphatase, i-PTH intact parathyroid hormone, PHPT primary hyperparathyroidism

Table 3

Genetic profile of patients with pathogenic germline variants (n = 11).
Patient	Gene	Chromosome	Exon	Variant	Protein	Variant type	ACMG	Previously reported (Clinvar / Pubmed *)
Case 1	MEN 1	11	10	c.1366-2A > G p?	---------	Splice variant	Pathogenic	VCV000403832.2 *
Case 2	MEN 1	11	10	c.1366-2A > G p?	---------	Splice variant	Pathogenic	VCV000403832.2 *
Case 3	MEN 1	11	10	c.1366-2A > G p?	---------	Splice variant	Pathogenic	VCV000403832.2 *
Case 4	MEN1	11	10	c.1366-2A > GP?	-----------	Splice variant	Pathogenic	VCV000403832.2 *
Case 5	MEN 1	11	2	c.247_250del CTGT	p.Ile85SerfsTe r33	Frameshift	Pathogenic	VCV000016693.18 *
Case 6	MEN 1	11	13	c.1763C > T,	p.S588L	Missense	Pathogenic	Misgar, et al [26] **
Case 7	MEN1	11	10	c.415 C > T	p.H139Y	Missense	Pathogenic	Carvahlo, et al [27] **
Case 8	CDC 73	1	7	codon 222 CGA (Arg) > TGA	----------	Stop codon	Pathogenic	Cetani, et al [28] **
Case 9	CDC 73	1	5	c.415C > T at codon 139)	R139X	Stop codon	Pathogenic	Bradley, et al [29] **
Case 10	CDC 73	1	5	c.687_688dellAG	p.Arg229Serfs37	Missense	Pathogenic	Van der Tuin, et al [30] **
Case 11	CDC73	1	1	c76delA	p.Ile26SerfsX11	Missense	pathogenic	Howell, et al [31] **
ACMG, American College of Medical Genetics

Table 4

Characteristics of patients with and without germline variants.
	Patients with germline variants (n = 11)	Patients without germline variants (n = 28)	P-value
Age (years)	25 (12–35)	30.5 (23–60)	0.029
Calcium (mg/dl)	12.9 (11.1–14.8)	12.0 (10.5–14.2)	0.041
Phosphorus (mg/dl)	2.3 (1.59–3.6)	2.21 (1.08–3.66)	0.334
ALP (U/L)	332 (97-4135)	134 (86–992)	0.004
iPTH (pg/ml)	250 (107–1900)	173 (89-1751)	0.179
24 hr Urinary Calcium (mg/day)	600 (296–814)	414.5 (167–1135)	0.029
Renal disease, n (%)	7 (63.36)	19 (67.85)	0.801
Skeletal disease, n (%)	7 (63.36)	8 (28.57)	0.043
Multiglandular disease, n (%)	4 (45.45)	6(21.42)	0.134
Data expressed as median (Range) unless specified
ALP alkaline phosphatase, iPTH intact parathyroid hormone
Significant p vaules are in bold (p < 0.05)

In this study, we describe a well-defined cohort of 39 patients who presented with features indicative of FHPT. To the best of our knowledge, this is the largest cohort of patients with suspected FHPT reported from India, where a customised gene panel related to FHPT was studied. We identified nine germline variants in 11 participants (28.2%), seven in MEN 1, and four in CDC 73. All these germline variants have been previously reported as pathogenic. Our sample's most common confirmed genetic disorder was MEN1, followed by CDC73.

The prevalence of germline variants found in our study is higher than reported by previous studies conducted in individuals with clinical diagnoses of FHPT. In a recent study involving a Mediterranean cohort of 40 patients, germline variants were reported in 22.5% [32]. Other studies in different populations have reported variable prevalence of germline variants: 9.3% in the American cohort [33], 15% in South Australia [10], and 26% in New Zealand [10]. One of the largest studies to date identified 19 pathogenic germline variants (11CASR, 6 MEN1, 1 CDC73, and 1 AP2S1) in 121 British patients with suspected FHPT (16%) [34]. For two reasons, the results of different studies are hardly comparable. Firstly, the authors used different criteria for FHPT, and secondly, the genes assessed differed between the studies [10, 34, 35]. The average percentage of MEN1 pathogenic variants in PHPT has been reported to be 15–21% (36, 37). Our results are consistent with these studies, as we observed MEN1 pathogenic variants in 17.9% of participants. However, in a recent study involving 40 patients [32], none had the MEN1 pathogenic variant. Similarly, only one MEN1 mutation was found in all the genes studied in a cohort of 29 Finnish patients with suspected FHPT (3%) [42]. The most common MEN1 pathogenic variant in our study was splice variant c.1366-2A > G p? observed in 4 out of 7 unrelated participants. In these patients, adenine is replaced by guanine at codon 1366. Out of these 4 participants, 2 had microprolactinoma.

Data regarding the prevalence of pathogenic germline CDC73 variants in PHPT patients are scarce. We observed pathogenic germline CDC73 variants in four (10.2%) patients. This is almost similar to a study reported by Van Der et al, [30] in which pathogenic germline CDC73 variants were identified in 11 of the 89 PHPT patients (12.4%). In this study, 10 of the 11 patients were male (91%). In a case series from Western India involving 7 patients with germline CDC73 variants, there were 4 males and 3 females. In our study, there were 2 males and 2 females. In our study, all 4 patients had uniglandular disease. This is consistent with the case series from Western India, which reported uniglandular disease in all 7 patients [38]. In our study, 2 participants had features of HPT-JT (one had multiple uterine fibroids, and one had bilateral renal cysts). In the case series from Western India, renal cysts were present in 3 patients, jaw tumours in 2 patients and uterine endometrial involvement in 2 patients. Out of 11 patients with pathogenic germline CDC73 variants, Van Der et al [30] reported HPT- JT in 3 patients, renal abnormalities in 1 patient and uterine abnormalities in none. In our patients with germline CDC73 variants, family history of PHPT was positive in 2/4 (50%). Previous study has reported a family history of PHPT in 73% of CDC73 mutation carriers (30). Previous studies have associated atypical parathyroid tumours with mutations in CDC73 (39). None of our patients had atypical parathyroid tumours. In a recent study [30], germline variants in CDC73 were not found in 11 patients with atypical parathyroid tumours.

We found several clinical traits that were significantly more frequent in patients with germline variants. Patients with germline variants were younger and had higher serum calcium and ALP. A study [43] reported higher calcium and PTH concentrations in patients with a positive genetic test compared to the group with a negative test, but this was not statistically significant. In addition, skeletal disease was more common in patients with germline variants. The earlier onset of disease in genetically driven PHPT leads to more skeletal involvement in the form of osteoporosis and subperiosteal bone resorption. Burgess et al [40] has reported that reduction in bone mass is evident in most women with MEN1 by 35 years of age. Eller C et al [41] reported that MEN1-related PHPT patients show more severe bone involvement than sporadic PHPT. Our study found no statistically significant difference between renal disease in patients with a positive genetic mutation. This is consistent with that reported by [41] Eller C et al.

Limitations: We have not tested our participants for FHH forms (caused by variants of CASR, GNA11, or AP2S1), neonatal severe hyperparathyroidism, and other forms caused by several genes classified as FIHP due to lack of funds. Also, we had not tested family members of patients with pathogenic variants.

In conclusion, we found a remarkable prevalence of genetic variants in our cohort with features suggestive of FHPT. This is consistent with the hypothesis that FHPT is probably an underdiagnosed entity owing to a limited number of genetic studies performed in routine clinical practice, non-standardized genetic screening, and an insufficient understanding of the genetics of PHPT. We suggest genetic testing in patients with PHPT presenting any risk characteristics considered in our study's inclusion criteria.

Financial Interest

The authors have no relevant financial or non-financial interests to disclose.

Ethics Approval:

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Ethical clearance was taken from the institutional Ethical committee with IEC/ SKIMS protocol # RP 208/202

Consent to Participate:

Informed consent was obtained from all individual participants included in the study

Consent to Participate

has been received from all participants in the study.

Funding:

The work was funded by the Endocrine Society of India.

Author Contribution

AQ, RAM, and AC wrote the main manuscript. IAB, MIB, AIW, MAW, and AAM prepared tables 1, 2, 3, and 4. All authors reviewed the manuscript.

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No competing interests reported.

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Molecular genetics in familial primary hyperparathyroidism: A study from Northern India

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