Question: What is (are) Fumarase deficiency ?
Answer: Fumarase deficiency is an inherited condition that primarily affects the nervous system, especially the brain. Affected infants may have microcephaly, abnormal brain structure, severe developmental delay, weak muscle tone (hypotonia), failure to thrive, seizures, and/or distinctive facial features. Other signs and symptoms may include hepatosplenomegaly, an excess of red blood cells (polycythemia), and/or or deficiency of white blood cells (leukopenia). Affected individuals usually survive only a few months, but a few have lived into early adulthood. This condition is caused by mutations in the FH gene and is inherited in an autosomal recessive manner. No effective treatment is currently available.
Source: GARD

Question: What are the symptoms of Fumarase deficiency ?
Answer: What are the signs and symptoms of Fumarase deficiency? Most newborns with fumarase deficiency show severe neurologic abnormalities, including poor feeding, failure to thrive, and poor muscle tone (hypotonia). Early-onset infantile encephalopathy (altered brain structure or function), seizures, and severe developmental delay with microcephaly are also common. Other signs and symptoms may include infantile spasms, abnormal posturing of the limbs, and autistic features. Distinctive facial features have been reported in some affected individuals and have included an unusually prominent forehead (frontal bossing); low-set ears; a small jaw (micrognathia); widely-spaced eyes (ocular hypertelorism); depressed nasal bridge; and high-arched palate. Other findings in affected individuals can include neonatal polycythemia (an excess of red blood cells); leukopenia (deficiency of white blood cells); neutropenia; enlarged liver and spleen (hepatosplenomegaly); and pancreatitis. Many children with this condition do not survive infancy or childhood. Those surviving beyond childhood have severe psychomotor deficits. The Human Phenotype Ontology provides the following list of signs and symptoms for Fumarase deficiency. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Agenesis of corpus callosum - Aminoaciduria - Anteverted nares - Autosomal recessive inheritance - Cerebral atrophy - Cholestasis - Choroid plexus cyst - Cutaneous leiomyoma - Decreased subcutaneous fat - Depressed nasal bridge - Failure to thrive - Frontal bossing - Hepatic failure - High palate - Hypertelorism - Hypoplasia of the brainstem - Intellectual disability, profound - Lactic acidosis - Metabolic acidosis - Microcephaly - Muscular hypotonia - Neurological speech impairment - Open operculum - Optic atrophy - Pallor - Polycythemia - Polymicrogyria - Relative macrocephaly - Status epilepticus - Visual impairment - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Fumarase deficiency ?
Answer: What causes fumarase deficiency? Mutations in the FH gene cause fumarase deficiency. The FH gene provides instructions for making an enzyme called fumarase, which participates in a series of reactions allowing cells to use oxygen and generate energy. Mutations in the FH gene disrupt the enzyme's ability to do its job. Disruption of the process that generates energy for cells is particularly harmful to cells in the developing brain, thus resulting in the signs and symptoms of fumarase deficiency.
Source: GARD