Muscular Dystrophy-Dystroglycanopathy (Congenital with Brain and Eye Anomalies), Type A, 1

Alternative Names

  • MDDGA1
  • Walker-Warburg Syndrome or Muscle-Eye-Brain Disease, POMT1-Related
  • Hydrocephalus, Agyria, and Retinal Dysplasia
  • HARD Syndrome
  • Cerebroocular Dysplasia-Muscular Dystrophy Syndrome
  • COD-MD Syndrome
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WHO-ICD-10 version:2010

Congenital malformations, deformations and chromosomal abnormalities

Congenital malformations of the nervous system

OMIM Number

236670

Mode of Inheritance

Autosomal recessive

Gene Map Locus

9q34.13

Description

Walker-Warburg syndrome is a recessive autosomal disorder characterized by congenital muscular dystrophy, severe brain malformation, and structural eye abnormalities. It is also known by the acronym HARD +/- E syndrome (hydroencephalus, agyri, retinal dysplasia, plus or minus "e" for encephalocele). Clinical features include a malformed head, small eyes, cataracts, retinal abnormalities, and muscle weakness. The brain manifests cobblestone lissencephaly with agenesis of the corpus callosum, cerebellar hypoplasia, hydrocephaly, and sometimes encephalocele. Seizures may occur. Encephalocele may be present as well. Microscopic examination reveals that the cells and tissues of the brain develop in a highly disorganized fashion. Life expectancy of patients with Walker-Warburg syndrome is usually less then 1 year.

Molecular Genetics

Walker-Warburg syndrome is caused by mutation in the POMT1 gene encoding protein O-mannosyltransferase. It is genetically heterogeneous, and approximately 20% of the patients show POMT1 mutations. The family of mammalian O-mannosyltransferases includes two enzymes, POMT1 and POMT2, which are thought to be essential for muscle and neural development. O-mannosylation is an important modification of proteins in various fundamental physiological processes. During embryogenesis, the murine POMT1 gene is prominently expressed in the neural tube, the developing eye, and the mesenchyme. These sites of expression correlate with those in which the main tissue alterations are observed in Walker-Warburg syndrome patients. The POMT1 gene contains 20 exons, spans about 20 kb, and is mapped to chromosome 9q34.1.

Epidemiology in the Arab World

View Map
Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
236670.1QatarUnknown Intellectual disability, profound; Type...NM_007171.3:c.1456delTHomozygousAutosomal, Recessivevan Reeuwijk et al. 2006
236670.2Saudi ArabiaFemaleYesYes Hydrocephalus; Seizure; Global developme...NM_001077365.2:c.280+1G>THomozygousAutosomal, RecessiveShaheen et al. 2017 Patient had a simila...
236670.3Saudi ArabiaUnknownYesYes Hydrocephalus; StillbirthNM_001077365.2:c.2113_2114delHomozygousAutosomal, RecessiveShaheen et al. 2017 Subject had 4 older ...
236670.4Saudi ArabiaUnknownYesYes Ventriculomegaly; Agenesis of cerebellar...NM_001077365.2:c.1175+4_1175+7delHomozygousAutosomal, RecessiveShaheen et al. 2017 Patient had a deceas...
236670.G.1LebanonUnknown Intellectual disability, profound; Type...NM_007171.3:c.314G>AHomozygousAutosomal, Recessivevan Reeuwijk et al. 2006 Two Lebanese patient...

Other Reports

Palestine

In 1997, Zlotogora analyzed 2000 Palestinian Arabic families and found that in 98 families at least one individual had congenital hydrocephalus and/or open neural tube defect. Among these families, 42 had congenital hydrocephalus without open neural tube defects; it was non-syndromal in 34 families and syndromal in the other eight (Meckel in 4, Warburg in 2, and an undiagnosed syndrome in each of the other 2 families). In the two families with Warburg syndrome there were three affected children who had hydrocephalus and one cephalocele, and in the last two families one child had hydrocephalus the other occipital cephalocele. Zlotogora (1997) indicated that Warburg syndrome was encountered in five Muslim families. The parents were first cousins in four of the families. In these families, 13 individuals were affected: 10 with hydrocephalus and three with occipital cephalocele.

Qatar

Fawzi et al. (2000) reported on the first case of WWS in Gulf people. The patient was an infant born to consanguineous Qatari parents. The parents were healthy, and had five other unaffected children. At birth, the child presented with generalized weakness, hypotonia, and cyanotic spells with bradycardia. He had mild dysmorphic features (low set ears, depressed nasal bridge, widely separated nipples), ocular abnormalities (bilateral megalo-cornea, left retinal detachment, and bilateral glaucoma), ambiguous genitalia (microphalus, bifid scrotum, and undescended testes), absence of deep tendon reflexes, poorly elicited neonatal reflexes, wide anterior fontanel, and splaying skull sutures. Biochemical investigations revealed a very high level of creatinine phosphokinase (1682 IU/l). CT brain revealed hydrocephalus, aqueductal stenosis, cerebellar vermis hypoplasia, and lissencephaly, while abdominal ultrasound showed a left multicystic kidney. At eight months of age, the child developed seizures. He died at one year of age.

[Fawzi M, Bessisso M, Omar F. Walker-Warburg syndrome: a case report of a Qatari patient. Qatar Med J. 2000; 9(2):66-7.]

Saudi Arabia

Currier et al. (2005) studied two consanguineous families affected with Walker-Warburg Syndrome, one each from Saudi Arabia and UAE. Sequencing on the POMT1 locus showed no mutations. In addiotion, homozygosity mapping revealed that neither of these families had identity by descent at the POMT1 locus

United Arab Emirates

See Saudi Arabia > Currier et al. 2005

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