Birk-Barel dimorphism intellectual disability syndrome ... (Birk-Barel Mental Retardation syndrome dymorphism -BIBAS-) - Gen KCNK9

Syndrome Birk-Barel is an inherited disease characterized by mental retardation, hypotonia, hyperactivity and unusual facial features. This syndrome was described in an Israeli Arab twin with intellectual disability, hypotonia and dysmorphic feature apparently maternal transmission. All affected individuals demonstrating moderate to severe intellectual disabilities and were hyperactive. Most developed dysphagia early stages of life until puberty and generalized hypotonia at an early age and continued weakness of the proximal musculature. Coordination, tendon reflexes, deep and superficial sense, and vibrations were normal and negative Babinski sign. Hearing and vision were normal, but all those affected had similar dysmorphic features with more marked in youth development stages.

In addition, affected individuals had mild atrophy of the temporal and masseter, dilated, thick eyebrows arched upward. Pointy ears and a prominent fold. The nasal bridge was tall and narrow, and broad nasal tip. The columela was normal, but the philtrum was extremely short, wide and thick in all patients. Maxillary and premaxillary regions were prominent with hypotonia jaw and micrognatia. The lips were thick with flail leaflets thereof. Most patients had a narrow palate, very full arcuate or submucous cleft and dysphonia. Owned large and protuberant incisors and all patients had neck, trunk and feet, narrow and elongated. Some children had mild joint contractures of the hips, elbows, and feet phalanges, which worsened with age. Most patients had pilonidal cysts. Muscle biopsies in two patients were consistent with spinal muscular atrophy. Mitochondria appeared normal in the electron microscopy examination, and no normal activity of the enzymes of the mitochondrial respiratory chain in muscle.

This process is due to a mutation in the gene KCNK9 (subfamily of potassium channels K, member 9), located on the long arm of chromosome 8 (8q24,3). This gene encodes the synthesis of proteins that function as potassium channel dependent pH.

This syndrome shows dominant inheritance with fatherly expression, meaning that a mutation in the maternal gene will result in the onset of disease, but a mutation in the paternal gene has no effect (silencing paternal inheritance).

Tests in IVAMI: in IVAMI perform detection of mutations associated with syndrome Birk-Barel intellectual disability with dimorphism, by complete PCR amplification of exons KCNK9 gene, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).