Medullary thyroid carcinoma in a 2-month-old male with multiple endocrine neoplasia 2B and symptoms of pseudo-Hirschsprung disease: a case report

Multiple endocrine neoplasia type 2: A reveiw

Multiple endocrine neoplasias are rare hereditary syndromes some of them with malignant potential. Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominant hereditary cancer syndrome due to germline variants in the REarranged during Transfection (RET) proto-oncogene. There are two distinct clinical entities: MEN 2A and MEN 2B. MEN 2A is associated with medullary thyroid carcinoma (MTC), phaeochromocytoma, primary hyperparathyroidism, cutaneous lichen amyloidosis and Hirschprung's disease and MEN 2B with MTC, phaeochromocytoma, ganglioneuromatosis of the aerodigestive tract, musculoskeletal and ophthalmologic abnormalities. Germline RET variants causing MEN 2 result in gain-of-function; since the discovery of the genetic variants a thorough search for genotype-phenotype associations began in order to understand the high variability both between families and within family members. These studies have successfully led to improved risk classification of prognosis in relation to the genotype, thus improving the management of the patients by thorough genetic counseling. The present review summarizes the recent developments in the knowledge of these hereditary syndromes as well as the impact on clinical management, including genetic counseling, of both individual patients and families. It furthermore points to future directions of research for better clarification of timing of treatments of the various manifestations of the syndromes in order to improve survival and morbidity in these patients.

Comparison of pediatric and adult medullary thyroid carcinoma based on SEER program

To compare the clinicopathological characteristics and survival outcomes of children and adult diagnosed with medullary thyroid carcinoma (MTC). MTC patients were extracted from the Surveillance, Epidemiology and End Results (SEER) database from 1998 to 2016, followed by stratification into pediatric (< 20 years) or adult (≥ 20 years) groups. In total, 2,197 patients (110 pediatric and 2087 adult) with MTC were identified. Pediatric patients were more likely to have localized stage (70.0% vs. 51.6%), negative regional nodes (48.2% vs. 30.8%) and receive total/subtotal thyroidectomy surgery (97.3% vs. 85.3%). Moreover, CSS and OS rates were significantly higher in pediatric patients (both P < 0.001). Multivariable Cox regression analysis revealed that adult patients were significantly correlated with worse CSS and OS rates [(CSS: HR 11.60, 95% CI 1.62–83.02, P = 0.015); (OS: HR 5.63, 95% CI 2.08–15.25, P = 0.001)]. Further stratified analysis indicated that pediatric group might have significant better CSS and OS for patients with more advanced stage. Patients in the pediatric group were more likely to have earlier stage. Moreover, the prognosis of pediatric MTC patients was significantly better than that in adult patients.

Identification of intestinal ganglioneuromatosis leads to early diagnosis of MEN2B: role of rectal biopsy

BACKGROUND/PURPOSE

Gastrointestinal symptoms are very common in patients with multiple endocrine neoplasia type 2B (MEN2B) syndrome. Herein, we present a case of intestinal ganglioneuromatosis (IGN) in MEN2B syndrome and a systematic literature review with a special focus on gastrointestinal symptoms prior to the diagnosis of MEN2B.

METHODS

Literature search was performed (years 1966-2015) using the "Pubmed" and "Scopus" databases. Search terms used were gastrointestinal, intestinal and MEN2B.

RESULTS

Literature search revealed 188 publications on MEN2B patients with gastrointestinal symptoms, providing a total of 55 patients including our own case. The far most common gastrointestinal symptom was constipation (72.7%). The onset of gastrointestinal symptoms occurred in 29 out of 55 cases (52.3%) below the age of 1year. However, MEN2B diagnosis was established at a median age of 13.0years (range 0-46years). The histological finding of IGN led to the diagnosis of MEN2B In 15 of 55 patients (27.3%) at a median age of 3years (range 0-31years).

CONCLUSION

Paying close attention to gastrointestinal problems in early childhood and taking a rectal biopsy that precisely screens for IGN offers the chance of diagnosing MEN2B syndrome early in infancy.

Medullary thyroid carcinoma: a review on ethical considerations in treatment of children

Thyroid carcinoma is the most common malignancy of the endocrine system and it accounts approximately 1%-3% of all human cancers. Among the three subtypes of thyroid cancers, medullary thyroid carcinoma (MTC) is the most common cause of death in patients with multiple endocrine neoplasia (MEN) type 2A (MEN2A), MEN type 2B (MEN2B) and familial medullary thyroid carcinoma (FMTC). Generally, MTC accounts for up to 10% of all types of thyroid cancers. It is one of the aggressive forms of thyroid carcinoma which is manifested in childhood ages more than adults, and it comprises about 17% of all pediatric thyroid cancer. Like the other cancers, prevention of MTC is easier than its cure. In the recent decades (from 1993) the diagnosis of asymptomatic child carrying RET mutations in the affected families by MTC, has been provided by genetic screening, and prophylactic thyroidectomy is an efficacy therapeutic procedure. On the one hand, according to near the complete penetrance of the disease and its onset in the early years of life, it is required to accelerate the protection of at-risk children with relative affected by MTC and on the other hand, there are several obstructions to MTC treatment including: 1) the proband's refusal to disclose the RET mutation genetic testing results, 2) children's vulnerability because of their inability to participate in the informed consent, and 3) the existence of conflict between physicians and children's guardian. In this review article, the recommendations and ethical issues of MTC treatment in asymptomatic and at-risk children have been summarized.

Risk-reduction surgery in pediatric surgical oncology: A perspective

OBJECTIVE

A small percentage of pediatric solid cancers arise as a result of clearly identified inherited predisposition syndromes and nongenetic lesions. Evidence supports preemptive surgery for children with genetic [multiple endocrine neoplasia type 2 (MEN2), familial adenomatous polyposis syndrome (FAP), hereditary nonpolyposis colorectal cancer (HNPCC), and hereditary diffuse gastric cancer (HDGC) and nongenetic [thyroglossal duct cysts (TGDC), congenital pulmonary airway malformations (CPAM), alimentary tract duplication cysts (ATDC), and congenital choledochal cysts (CCC)] developmental anomalies. Our aim was to explore the utility of risk reduction surgery to treat and prevent cancer in children.

METHODS

A systematic review of the available peer-reviewed literature on PubMed was performed using a PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) search strategy, where possible. Search items included "risk reduction surgery", "hereditary cancer predisposition syndrome", "multiple endocrine neoplasia type 2", "familial adenomatous polyposis", "hereditary nonpolyposis colorectal cancer", "hereditary diffuse gastric cancer", "thyroglossal duct cysts", congenital pulmonary airway malformations", "alimentary tract duplication cysts", "malignant transformation", and "guidelines".

RESULTS

We identified 67 articles that met the inclusion criteria describing the indications for prophylactic surgery in surgical oncology. For the genetic predisposition syndromes, 7 studies were related to professional endorsed guidelines, 7 were related to surgery for MEN2, 11 were related to colectomy for FAP, 6 were related to colectomy for HNPCC, and 12 related to gastrectomy for HDGC. Articles for the nongenetic lesions included 5 for techniques related to TGDC resection, 9 for surgery for CPAMs, and 10 for resection of ATDCs. Guidelines and strategies varied significantly especially related to the extent and timing of surgical intervention; the exception was for the timing of thyroidectomy in children with MEN2.

CONCLUSION

Current evidence supporting prophylactic surgery in the management of pediatric cancer predisposition syndromes and nongenetic lesions is best delineated for thyroidectomy to prevent medullary thyroid cancer in children with MEN2 (Strength of Recommendation Grade B/C). Despite the lack of pediatric specific evidence-based recommendations regarding the appropriate extent and timing for risk-reduction surgery for FAP, HNPCC, HDGC and nongenetic anomalies, our review represents an opportunity towards understanding the postgenomic development of these lesions and provides current indications and techniques for preemptive cancer prevention surgery in children.

Surgical curability of medullary thyroid cancer in multiple endocrine neoplasia 2B: a changing perspective

OBJECTIVE

This investigation aimed at exploring the suitability of nonendocrine manifestations preceding medullary thyroid cancer (MTC) for early diagnosis of multiple endocrine neoplasia type 2B (MEN 2B).

BACKGROUND

MEN 2B patients, running a high risk of metastatic MTC, must be diagnosed early for biochemical cure.

METHODS

Forty-four MEN 2B patients carrying inherited (3 patients) and de novo (41 patients) M918T RET mutations were examined for signs and symptoms prompting MEN 2B.

RESULTS

All 3 patients with inherited mutations were diagnosed before the age of 1 year and cured of their C-cell disease. Among 41 patients with de novo mutations, MEN 2B was diagnosed in 12 patients after recognition of nonendocrine manifestations [intestinal ganglioneuromatosis (6 patients), oral symptoms (5 patients), ocular ("tearless crying") (4 patients), and skeletal stigmata (1 patient) alone or concomitantly]. In the remaining 29 patients with de novo mutations, the diagnosis of MEN 2B was triggered by symptomatic MTC (28 patients) or pheochromocytoma (1 patient). The former patients, being significantly (P < 0.001) younger (means of 5.3 vs 17.6 years) and having lower calcitonin levels (means of 115 vs 25,519 pg/mL), smaller tumors (67% vs 0% were ≤10 mm) and less often extrathyroidal extension (0% vs 81%), lymph node (42% vs 100%), and distant metastases (8% vs 79%), were biochemically cured more often (58% vs 0%).

CONCLUSIONS

MTC is curable in patients with de novo mutations when nonendocrine MEN 2B components are quickly appreciated and surgical intervention is performed before patients turn 4 years old.

Classification and diagnostic criteria of variants of Hirschsprung's disease

"Variants of Hirschsprung's disease" are conditions that clinically resemble Hirschsprung's disease (HD), despite the presence of ganglion cells in rectal suction biopsies. The diagnosis and management of these patients can be challenging. Specific histological, immunohistochemical and electron microscopic investigations are required to characterize this heterogeneous group of functional bowel disorders. Variants of HD include intestinal neuronal dysplasia, intestinal ganglioneuromatosis, isolated hypoganglionosis, immature ganglia, absence of the argyrophil plexus, internal anal sphincter achalasia and congenital smooth muscle cell disorders such as megacystis microcolon intestinal hypoperistalsis syndrome. This review article systematically classifies variants of HD based on current diagnostic criteria with an additional focus on pathogenesis, epidemiology, clinical presentation, management and outcome.

Diffuse intestinal ganglioneuromatosis in a child

A 7 year old male with a history of congenital neutropenia and growth hormone deficiency presented with abdominal pain, fevers, and diarrhea. Imaging and endoscopy revealed significant inflammation of the ascending colon with stenosis at the level of the hepatic flexure. A right hemicolectomy was performed, and pathologic findings were consistent with diffuse intestinal ganglioneuromatosis. Due to recurrent mass effect at the intestinal anastomotic site detected radiologically, a second intestinal resection was performed 7 months later. Genetic testing was negative for mutations in the RET protooncogene, NF1 and PTEN tumor suppressor genes. We report a case of diffuse intestinal ganglioneuromatosis in a child with congenital neutropenia.

Medullary thyroid cancer in a 9-week-old infant with familial MEN 2B: Implications for timing of prophylactic thyroidectomy

BACKGROUND

Patients with Multiple Endocrine Neoplasia type 2 (MEN 2) are at high risk of developing aggressive medullary thyroid carcinoma (MTC) in childhood, with the highest risk in those with MEN type 2B (of whom >95% have an M918T RET proto-oncogene mutation). Metastatic MTC has been reported as young as 3 months of age. Current guidelines recommend prophylactic thyroidectomy within the first year of life for MEN 2B.

PATIENT FINDINGS

We report a 9-week-old infant with MTC due to familial MEN 2B. A full-term male infant, born to a mother with known MEN 2B and metastatic MTC, had an M918T RET proto-oncogene mutation confirmed at 4 weeks of age. He underwent prophylactic total thyroidectomy at 9 weeks of age. Pathology showed a focal calcitonin-positive nodule (2.5 mm), consistent with microscopic MTC.

SUMMARY

This case highlights the importance of early prophylactic thyroidectomy in MEN 2B. Although current guidelines recommend surgery up to a year of life, MTC may occur in the first few weeks of life, raising the question of how early we should intervene. In this report, we discuss the risks, benefits and barriers to performing earlier thyroidectomy, soon after the first month of life, and make suggestions to facilitate timely intervention. Prenatal anticipatory surgical scheduling could be considered in familial MEN 2B. Multidisciplinary collaboration between adult and pediatric specialists is key to the optimal management of the infant at risk.

Histochemical staining for intestinal dysganglionosis: over 30 years experience with more than 1,500 biopsies

PURPOSE

Intestinal dysganglionosis are a group of anomalies of the enteric nervous system that constitute infrequent but severe forms of constipation. Histochemical stainings are the gold standard diagnostic procedure for intestinal dysganglionosis. This study describes our experience with histochemistry in a large series of patients.

METHODS

Between 1977 and 2010, 1,589 biopsies from children with persistent chronic constipation were studied. The specimens were snap frozen, sectioned and stained with acetylcholinesterase (AChE), acetylcholinesterase counterstained with hematoxilin and succinic dehydrogenase (SDH) histochemical stainings.

RESULTS

Among the 1,589 biopsies, 946 (59.5%) were rectal biopsies, 242 (15.2%) were internal sphincter biopsies, 346 (21.8%) were intestinal mapping studies and 42 (2.7%) of them were colon specimens from surgical resections. From the rectal biopsy group, 544 (57.5%) patients were reported as normal. Hirschsprung disease was found in 163 (17.2%) patients with a median age at diagnosis of 8 months and a male to female ratio of 3:1. Intestinal neuronal dysplasia was found in 162 (17.2%) patients, hypoganglionosis in 3 (0.3%) of them and ganglioneuromatosis in 1 (0.1%). In 73 (7.7%) patients, the biopsy was not conclusive for different reasons. 34 out of the 42 resected colon specimens were Hirschsprung disease. Intestinal neuronal dysplasia was found in the proximal segment of the aganglionic bowel in 15 out of 34 (44%) patients. All the aganglionic resected colon specimens had a previous aganglionic rectal biopsy. There were no false positive results in this group.

CONCLUSIONS

Histochemical stainings continue to be the gold standard in the diagnosis of intestinal dysganglionosis. The combination of two histochemical staining techniques provides a high level of accuracy in the diagnosis of intestinal dysganglionosis.

Clinical value of 18-fluorine-fluorodihydroxyphenylalanine positron emission tomography/computed tomography in the follow-up of medullary thyroid carcinoma

BACKGROUND

18-Fluorine-fluorodihydroxyphenylalanine positron emission tomography ((18)F-DOPA PET) is a sensitive method for detecting medullary thyroid carcinoma (MTC). The advent of PET/computed tomography (CT) has enabled more sensitive and specific lesion identification using various tracers in many other tumors. The aim of this study was therefore to test the hypothesis that combined (18)F-DOPA PET/CT more accurately detects MTC lesions than each modality does alone.

METHODS

Twenty-eight consecutive (18)F-DOPA PET, CT, and (18)F-DOPA PET/CT scans of patients followed up for sporadic MTC or multiple endocrine neoplasia 2 syndrome-associated MTC were reviewed retrospectively in randomized sequence by two blinded readers, one a nuclear medicine physician and the other a radiologist, with extensive experience interpreting such images.

RESULTS

Of 18 lesions detected concurrently by the three modalities, PET identified all as positive for MTC, but was unable to definitively localize 4 (22%) lesions. CT could definitively localize all 18 lesions, but could not definitively diagnose or exclude MTC in 6 (33%) lesions. Further, CT falsely identified as MTC-negative one lesion that was judged to be MTC-positive by both PET and PET/CT. Only PET/CT scans accurately characterized and localized all 18 lesions. On a per patient basis, the sensitivity of (18)F-DOPA PET/CT for MTC was 74% and the specificity, 100%. In the present series, no truly MTC-positive (18)F-DOPA PET/CT case was found in patients with basal human calcitonin (hCt) levels under 60 pg/mL, and conversely, no truly MTC-negative PET/CT case was found in patients with basal hCt over 120 pg/mL. Between hCt concentrations of 60 and 150 pg/mL true-negative, false-negative, and true-positive scans all were obtained. (18)F-DOPA PET/CT had 100% sensitivity and specificity when hCt at the time of scanning was over 150 pg/mL, the threshold at which the 2009 American Thyroid Association guidelines recommend performing additional imaging including (18)F-DOPA PET/CT.

CONCLUSIONS

(18)F-DOPA PET/CT allows for a more accurate diagnosis and localization of MTC lesions than do (18)F-DOPA PET or CT alone. Supporting the recent American Thyroid Association recommendations on additional imaging in MTC, (18)F-DOPA PET/CT appears to have 100% sensitivity in patients with hCt over 150 pg/mL.

Early diagnosis of multiple endocrine neoplasia type 2B: a challenge for physicians

BACKGROUND

The hereditary form of medullary thyroid carcinoma may occur isolated as a familial medullary thyroid carcinoma (FMTC) or as part of Multiple Endocrine Neoplasia 2A (MEN2A) and 2B (MEN2B). MEN2B is a rare syndrome, its phenotype may usually, but not always, be noted by the physician. In the infant none of the MEN2B characteristics are present, except by early gastrointestinal dysfunction caused by intestinal neuromas. When available, genetic analysis confirms the diagnosis and guides pre-operative evaluation and extent of surgery. Here we report four cases of MEN2B in which the late diagnosis had a significant impact in clinical evolution and, potentially, in overall survival.

CASE REPORT

We report four cases, 2 men and 2 women, with differences in their phenotypes and with a late diagnosis. The first case has a history of severe gastrointestinal obstruction requiring a surgery intervention two days after his birth. The second told had nodules in the oral mucosa and constipation since childhood. The third case referred a history of constipation from birth until 5 months of life. The fourth has had a history of chronic constipation since childhood.

DISCUSSION

New concepts have emerged since the RET oncogene was identified in 1993 as the responsible gene for hereditary medullary thyroid carcinoma. The majority of MEN2B individuals have M918T mutation in the exon 16 of RET, with a few cases having a mutation A883F or the association of V804M with E805K, Y806C or S904C mutations. The consensus classifies the RET mutation in codon 918 as of highest risk and recommends total thyroidectomy and central lymph node dissection until 6 months after birth. A fast and precise diagnosis is essential to reach these goals. The identification of early manifestations such as intestinal ganglioneuromatosis and oral mucosal neuromas should prompt the physician to initiate an investigation for multiple endocrine neoplasia type 2B.

CONCLUSION

The diagnosis of MEN2B is very important to allow appropriate investigation of associated diseases and to allow counseling and appropriate screening of relatives for a RET mutation. Even patients with MEN2B, which often have typical physical features, may not be properly recognized and be followed as a sporadic case. Based on this, all suspicious cases of multiple endocrine neoplasia should undergo a molecular genetic test.

Multiple endocrine neoplasia type 2 RET protooncogene database: repository of MEN2-associated RET sequence variation and reference for genotype/phenotype correlations

Multiple endocrine neoplasia type 2 (MEN2) is an inherited, autosomal-dominant disorder caused by deleterious mutations within the RET protooncogene. MEN2 RET mutations are mainly heterozygous, missense sequence changes found in RET exons 10, 11, and 13-16. Our group has developed the publicly available, searchable MEN2 RET database to aid in genotype/phenotype correlations, using Human Genome Variation Society recommendations for sequence variation nomenclature and database content. The MEN2 RET database catalogs all RET sequence variation relevant to the MEN2 syndromes, with associated clinical information. Each database entry lists a RET sequence variation's location within the RET gene, genotype, pathogenicity classification, MEN2 phenotype, first literature reference, and comments (which may contain information on other clinical features, complex genotypes, and additional literature references). The MEN2 phenotype definitions were derived from the International RET Mutation Consortium guidelines for classification of MEN2 disease phenotypes. Although nearly all of the 132 RET sequence variation entries initially cataloged in the database were from literature reports, novel sequence variation and updated phenotypic information for any existing database entry can be submitted electronically on the database website. The database website also contains links to selected MEN2 literature reviews, gene and protein information, and RET reference sequences. The MEN2 RET database (www.arup.utah.edu/database/MEN2/MEN2_welcome.php) will serve as a repository for MEN2-associated RET sequence variation and reference for RET genotype/MEN2 phenotype correlations.

Constitutive RET tyrosine kinase activation in hereditary medullary thyroid cancer: clinical opportunities

The ground-breaking discovery of genotype-phenotype relationships in hereditary medullary thyroid cancer has greatly facilitated early prophylactic thyroidectomy. Its timing depends not solely on a positive gene test but, more importantly, on the type of the REarranged during Transfection (RET) mutation and its underlying mode of RET receptor tyrosine kinase activation. In the past decade, the therapeutic corridor opened by molecular information has been defined down to a remarkable level of detail. Based on mutational risk profiles, preemptive thyroidectomy is recommended at 6 months of age for carriers of highest-risk mutations, before the age of 5 years for carriers of high-risk mutations, and before the age of 5 or 10 years for carriers of least-high-risk mutations. Additional lymph node dissection may not be needed in the absence of increased preoperative basal calcitonin levels. Better comprehension of RET function should enable the design of targeted therapies for RET carriers beyond surgical cure in whom the DNA-based 'window of opportunity' has been missed.

Medullary thyroid cancer: management guidelines of the American Thyroid Association

BACKGROUND

Inherited and sporadic medullary thyroid cancer (MTC) is an uncommon and challenging malignancy. The American Thyroid association (ATA) chose to create specific MTC Clinical Guidelines that would bring together and update the diverse MTC literature and combine it with evidence-based medicine and the knowledge and experience of a panel of expert clinicians.

METHODS

Relevant articles were identified using a systematic PubMed search and supplemented with additional published materials. Evidence-based recommendations were created and then categorized using criteria adapted from the United States Preventive Services Task Force, Agency for Healthcare Research and Quality.

RESULTS

Clinical topics addressed in this scholarly dialog included: initial diagnosis and therapy of preclinical disease (including RET oncogene testing and the timing of prophylactic thyroidectomy), initial diagnosis and therapy of clinically apparent disease (including preoperative testing and imaging, extent of surgery, and handling of devascularized parathyroid glands), initial evaluation and treatment of postoperative patients (including the role of completion thyroidectomy), management of persistent or recurrent MTC (including the role of tumor marker doubling times, and treatment of patients with distant metastases and hormonally active metastases), long-term follow-up and management (including the frequency of follow-up and imaging), and directions for future research.

CONCLUSIONS

One hundred twenty-two evidence-based recommendations were created to assist in the clinical care of MTC patients and to share what we believe is current, rational, and optimal medical practice.

Medullary thyroid carcinoma identified within the first year of life in children with hereditary multiple endocrine neoplasia type 2A (codon 634) and 2B

CONTEXT

Early prophylactic thyroidectomy in patients with multiple endocrine neoplasia (MEN) type 2 offers the best chance for a normal life expectancy.

OBJECTIVE

To analyze the results of thyroidectomy performed during the first year of life in six patients with MEN 2A (codon 634) or MEN 2B (codon 918) syndrome.

DESIGN AND SETTING

A university hospital-based prospective study from 2001 to 2008.

SUBJECTS AND METHODS

Six family members affected either by MEN 2A (n=3) or MEN 2B (n=3) syndrome were identified through neonatal genetic screening.

RESULTS

Total thyroidectomy was performed at a median age of 0.8 year in the six patients, with central lymph node dissection in five. Bilateral millimetric medullary thyroid carcinoma (MTC) was found in all patients, with a unilateral lymph node micrometastasis in two of the three MEN 2B patients. Before thyroidectomy, MEN 2B patients had much higher basal serum calcitonin levels than those with MEN 2A and controls. After thyroidectomy, with a median follow-up of 3.3 years, the six patients had no evidence of persistent MTC.

CONCLUSION

Bilateral millimetric MTC may be present during the first year of life in these patients, with lymph node metastases also occurring in MEN 2B patients. These results support a total thyroidectomy at the age of about one year in MEN 2A (codon 634) children with an abnormal serum calcitonin level, and a total thyroidectomy with central neck dissection within the first weeks of life in MEN 2B patients.

Molecular alterations in hereditary and sporadic thyroid and parathyroid diseases

Thyroid and parathyroid diseases are fairly common and can be either hereditary or sporadic in nature. Tumors and tumor-like processes account for the majority of surgical pathology specimens in both of these endocrine organs. Molecular alterations are well known to occur in both the hereditary and the sporadic settings, and include alterations in tumor suppressor genes and oncogenes. The genetic pathways of tumors of parathyroid and thyroid are beginning to be well understood and are proving to be useful diagnostic, prognostic, and potential therapeutic targets. The molecular alterations in parathyroid and thyroid tumors and tumor-like processes are reviewed, with a focus on the potentially clinically useful diagnostic markers.