MedGen

X-linked sideroblastic anemia and ataxia is a rare condition characterized by a blood disorder called sideroblastic anemia and movement problems known as ataxia. This condition occurs only in males.

Sideroblastic anemia results when developing red blood cells called erythroblasts do not make enough hemoglobin, which is the protein that carries oxygen in the blood. People with X-linked sideroblastic anemia and ataxia have mature red blood cells that are smaller than normal (microcytic) and appear pale (hypochromic) because of the shortage of hemoglobin. This disorder also leads to an abnormal accumulation of iron in red blood cells. The iron-loaded erythroblasts, which are present in bone marrow, are called ring sideroblasts. These abnormal cells give the condition its name. Unlike other forms of sideroblastic anemia, X-linked sideroblastic anemia and ataxia does not cause a potentially dangerous buildup of iron in the body. The anemia is typically mild and usually does not cause any symptoms.

X-linked sideroblastic anemia and ataxia causes problems with balance and coordination that appear early in life. The ataxia primarily affects the trunk, making it difficult to sit, stand, and walk unassisted. In addition to ataxia, people with this condition often have trouble coordinating movements that involve judging distance or scale (dysmetria) and find it difficult to make rapid, alternating movements (dysdiadochokinesis). Mild speech difficulties (dysarthria), tremor, and abnormal eye movements have also been reported in some affected individuals. [from MedlinePlus Genetics]

Combined oxidative phosphorylation deficiency-44 (COXPD44) is an autosomal recessive mitochondrial disorder with multisystemic manifestations. Most affected individuals present in infancy or early childhood with global developmental delay, hypotonia, and abnormal movements. Most patients develop seizures, often associated with status epilepticus, and some patients may have optic atrophy. One patient with hypertrophic cardiomyopathy has been reported. Serum lactate may be increased, although that finding is inconsistent. Detailed biochemical analysis shows variable combined deficiencies of mitochondrial oxidative complexes that appear to be tissue-specific (summary by Wei et al., 2020). For discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060). [from OMIM]

Combined oxidative phosphorylation deficiency-59 (COXPD59) may present as a lethal infantile form of Leigh syndrome (see 256000) or as a milder disorder with hypertrophic cardiomyopathy, lactic acidosis, attention deficit-hyperactivity disorder (ADHD) and survival into adulthood (summary by Amarasekera et al., 2023). For a discussion of genetic heterogeneity of combined oxidative phosphorylation deficiency, see COXPD1 (609060). [from OMIM]

A deviation from normal signal on magnetic resonance imaging (MRI) of the basal ganglia. [from HPO]