Clinical and biochemical footprints of inherited metabolic diseases. IV. Metabolic cardiovascular disease

Clinical and biochemical footprints of inherited metabolic disease. XVI. Hematological abnormalities

Many classical inherited metabolic diseases (IMDs) are associated with significant hematological complications such as anemia or thrombosis. While these may not be the prominent presenting feature of these conditions, management of these issues is important for optimal outcomes in people with IMDs. Some disorders that are included in the nosology of inherited metabolic disorders, such as inherited disorders of red cell energy metabolism, have purely hematological features, and have typically been cared for by a hematologist. In the 16th issue of the Footprints series, we identified 265 IMDs associated with hematological abnormalities. We review the major hematological manifestations of IMDs, suggest further investigation of hematological findings, and discuss treatment options available for specific hematological complications of IMDs.

IGAm: A novel index predicting long-term survival in patients with early-diagnosed inherited metabolic disorders

OBJECTIVES

The childhood mortality rate for IMDs is approximately 25 % in populations with no expanded newborn screening program. Although the factors that increase mortality risk are known, an index predicting long-term survival has yet to be established.

METHODS

Two hundred sixty patients who were hospitalized during the first month of their life were screened, and 94 patients diagnosed with IMDs were included in the study. Clinical and laboratory data were assessed to identify any independent prognostic factors for overall survival.

RESULTS

Among the 38 patients with IMDs in the exitus group, the presence of dysmorphism, extremity abnormalities, respiratory distress, cyanosis, elevated transaminases, elevated INR, hypoglycemia, hypoalbuminemia, metabolic acidosis, electrolyte imbalance and anemia were associated with poorer survival. Elevated INR (Hazard Ratio [HR]: 0.17, 95 % CI: 0.03-0.87, p=0.034), hypoglycemia (HR: 0.48, 95 % CI: 0.25-0.91, p=0.026) and hypoalbuminemia (HR: 0.09, 95 % CI: 0.03-0.26, p<0.001) were the independent prognostic factors for survival after adjusting for confounding factors. For the prediction of survival, INR, glucose, and albumin were used to structure a novel index (IGAm = INR-Glucose-Albumin metabolic index). The median survival was shorter in the IGAm-high group (2 or 3 points) than in the IGAm-low group (p<0.001). Harrell's c-index was 0.73 for the IGAm index.

CONCLUSIONS

The devised novel IGAm index can predict long-term survival in patients with IMDs, with a high IGAm index being associated with higher mortality in patients with IMDs.

Clinical and biochemical footprints of inherited metabolic diseases. XIV. Metabolic kidney diseases

Kidney disease is a global health burden with high morbidity and mortality. Causes of kidney disease are numerous, extending from common disease groups like diabetes and arterial hypertension to rare conditions including inherited metabolic diseases (IMDs). Given its unique anatomy and function, the kidney is a target organ in about 10% of known IMDs, emphasizing the relevant contribution of IMDs to kidney disease. The pattern of injury affects all segments of the nephron including glomerular disease, proximal and distal tubular damage, kidney cyst formation, built-up of nephrocalcinosis and stones as well as severe malformations. We revised and updated the list of known metabolic etiologies associated with kidney involvement and found 190 relevant IMDs. This represents the 14th of a series of educational articles providing a comprehensive and revised list of metabolic differential diagnoses according to system involvement.

Clinical and biochemical footprints of inherited metabolic diseases. XIII. Respiratory manifestations

At any age, respiratory manifestations are a major cause of increased morbidity and mortality of inherited metabolic diseases (IMDs). Type and severity are extremely variable, this depending on the type of the underlying disorder. Symptoms and signs originating from upper or lower airways and/or thoracic wall and/or respiratory muscles involvement can occur either at presentation or in the late clinical course. Acute respiratory symptoms can trigger metabolic decompensation which, in turn, makes airway symptoms worse, creating a vicious circle. We have identified 181 IMDs associated with various types of respiratory symptoms which were classified into seven groups according to the type of clinical manifestations affecting the respiratory system: (i) respiratory failure, (ii) restrictive lung disease, (iii) interstitial lung disease, (iv) lower airway disease, (v) upper airway obstruction, (vi) apnea, and (vii) other. We also provided a list of investigations to be performed based on the respiratory phenotypes and indicated the therapeutic strategies currently available for IMD-associated airway disease. This represents the thirteenth issue in a series of educational summaries providing a comprehensive and updated list of metabolic differential diagnoses according to system involvement.

Clinical and biochemical footprints of inherited metabolic diseases. XII. Immunological defects

Immunological problems are increasingly acknowledged manifestations in many inherited metabolic diseases (IMDs), ranging from exaggerated inflammation, autoimmunity and abnormal cell counts to recurrent microbial infections. A subgroup of IMDs, the congenital disorders of glycosylation (CDG), includes CDG types that are even classified as primary immunodeficiencies. Here, we reviewed the list of metabolic disorders reported to be associated with various immunological defects and identified 171 IMDs accompanied by immunological manifestations. Most IMDs are accompanied by immune dysfunctions of which immunodeficiency and infections, innate immune defects, and autoimmunity are the most common abnormalities reported in 144/171 (84%), 44/171 (26%) and 33/171 (19%) of IMDs with immune system involvement, respectively, followed by autoinflammation 17/171 (10%). This article belongs to a series aiming at creating and maintaining a comprehensive list of clinical and metabolic differential diagnoses according to organ system involvement.

Clinical and biochemical footprints of inherited metabolic disorders. XI. Gastrointestinal symptoms

Inherited metabolic disorders presenting with gastrointestinal (GI) symptoms are characterized by the dysfunction of the esophagus, stomach, small and large intestines, and pancreas. We have summarized associations of signs and symptoms in 339 inherited metabolic diseases presenting with GI symptoms. Feeding difficulties represent the most common abnormality reported for IMDs with GI involvement (37%) followed by intestinal problems (30%), vomiting (22%), stomach and pancreas involvement (8% each), and esophagus involvement (4%). This represents the eleventh of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

Targeting lipid metabolism as a new therapeutic strategy for inherited cardiomyopathies

Inherited cardiomyopathies caused by pathological genetic variants include multiple subtypes of heart disease. Advances in next-generation sequencing (NGS) techniques have allowed for the identification of numerous genetic variants as pathological variants. However, the disease penetrance varies among mutated genes. Some can be associated with more than one disease subtype, leading to a complex genotype-phenotype relationship in inherited cardiomyopathies. Previous studies have demonstrated disrupted metabolism in inherited cardiomyopathies and the importance of metabolic adaptations in disease onset and progression. In addition, genotype- and phenotype-specific metabolic alterations, especially in lipid metabolism, have been revealed. In this mini-review, we describe the metabolic changes that are associated with dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM), which account for the largest proportion of inherited cardiomyopathies. We also summarize the affected expression of genes involved in fatty acid oxidation (FAO) in DCM and HCM, highlighting the potential of PPARA-targeting drugs as FAO modulators in treating patients with inherited cardiomyopathies.

Clinical and biochemical footprints of inherited metabolic disease. V. Cerebral palsy phenotypes

Cerebral palsy is the most common physical disability of childhood describing a heterogeneous group of neurodevelopmental disorders that cause activity limitation, but often are accompanied by disturbances of sensation, perception, cognition, communication and behavior, or by epilepsy. Inborn errors of metabolism have been reported in the literature as presenting with features of cerebral palsy. We reviewed and updated the list of metabolic disorders known to be associated with symptoms suggestive of cerebral palsy and found more than 150 relevant IEMs. This represents the fifth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnosis according to system involvement.

Clinical and biochemical footprints of inherited metabolic diseases. IX. Metabolic ear disease

Damages to the ear are very diverse and can depend on the type of inherited metabolic diseases (IMD). Indeed, IMDs can affect all parts of the auditory system, from the outer ear to the central auditory process. We have identified 219 IMDs associated with various types of ear involvement which we classified into five groups according to the lesion site of the auditory system: congenital external ear abnormalities, acquired external ear abnormalities, middle ear involvement, inner ear or retrocochlear involvement, and unspecified hearing loss. This represents the ninth issue in a series of educational summaries providing a comprehensive and updated list of metabolic differential diagnoses according to system involvement.

Clinical and biochemical footprints of inherited metabolic disorders: X. Metabolic myopathies

Metabolic myopathies are characterized by the deficiency or dysfunction of essential metabolites or fuels to generate energy for muscle contraction; they most commonly manifest with neuromuscular symptoms due to impaired muscle development or functioning. We have summarized associations of signs and symptoms in 358 inherited metabolic diseases presenting with myopathies. This represents the tenth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

Clinical and biochemical footprints of inherited metabolic diseases. VIII. Neoplasias

Cancer, caused by multiple cumulative pathogenic variants in tumor suppressor genes and proto-oncogenes, is a leading cause of mortality worldwide. The uncontrolled and rapid cell growth of the tumors requires a reprogramming of the complex cellular metabolic network to favor anabolism. Adequate management and treatment of certain inherited metabolic diseases might prevent the development of certain neoplasias, such as hepatocellular carcinoma in tyrosinemia type 1 or hepatocellular adenomas in glycogen storage disorder type 1a. We reviewed and updated the list of known metabolic etiologies associated with various types of benign and malignant neoplasias, finding 64 relevant inborn errors of metabolism. This is the eighth article of the series attempting to create a comprehensive list of clinical and metabolic differential diagnosis by system involvement.

Clinical and biochemical footprints of inherited metabolic disorders. VII. Ocular phenotypes

Ocular manifestations are observed in approximately one third of all inherited metabolic disorders (IMDs). Although ocular involvement is not life-threatening, it can result in severe vision loss, thereby leading to an additional burden for the patient. Retinal degeneration with or without optic atrophy is the most frequent phenotype, followed by oculomotor problems, involvement of the cornea and lens, and refractive errors. These phenotypes can provide valuable clues that contribute to its diagnosis. In this issue we found 577 relevant IMDs leading to ophthalmologic manifestations. This article is the seventh of a series attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

Clinical and biochemical footprints of inherited metabolic diseases. VI. Metabolic dermatoses

Cutaneous signs and symptoms may facilitate the diagnosis or can help in identifying complications or side effects of overtreatment of inherited metabolic diseases. The principal manifestations can be grouped into vascular lesions, ichthyosis, papular and nodular skin lesions, abnormal pigmentation, photosensitivity, skin laxity, hair shaft involvement, and nail abnormalities. We have summarized associations of these cutaneous signs and symptoms in 252 inherited metabolic diseases. This represents the sixth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.