Rare missense variant p.Ala505Ser in the ZAK protein observed in a patient with split-hand/foot malformation from a non-consanguineous pedigree.

Objective: Split-hand/foot malformation (SHFM) is a rare, often debilitating, congenital limb malformation. A single nucleotide polymorphism within the leucine zipper containing kinase AZK () gene was recently associated with SHFM in two consanguineous Pakistani pedigrees. We hypothesized that additional unrelated patients with the phenotype may carry a pathogenic mutation in .

Dysregulations of sonic hedgehog signaling in MED12-related X-linked intellectual disability disorders.

Background: Mutations in mediator of RNA polymerase II transcription subunit 12 homolog (MED12, OMIM 300188) cause X-linked intellectual disability (XLID) disorders including FG, Lujan, and Ohdo syndromes. The Gli3-dependent Sonic Hedgehog (SHH) signaling pathway has been implicated in the original FG syndrome and Lujan syndrome. How are SHH-signaling defects related to the complex clinical phenotype of MED12-associated XLID syndromes are not fully understood.

Missense Mutation R338W in ARHGEF9 in a Family with X-linked Intellectual Disability with Variable Macrocephaly and Macro-Orchidism.

Non-syndromal X-linked intellectual disability (NS-XLID) represents a broad group of clinical disorders in which ID is the only clinically consistent manifestation. Although in many cases either chromosomal linkage data or knowledge of the >100 existing XLID genes has assisted mutation discovery, the underlying cause of disease remains unresolved in many families. We report the resolution of a large family (K8010) with NS-XLID, with variable macrocephaly and macro-orchidism.

Pelizaeus-Merzbacher syndrome: neurocognitive function in a family with carrier manifestations.

A Cajun kindred with Pelizaeus-Merzbacher disease was found to have a p.Q128X mutation in exon 3B of proteolipid protein 1 (PLP1). The affected males were globally delayed in development, nonambulatory, and severely dysarthric.

The original Lujan syndrome family has a novel missense mutation (p.N1007S) in the MED12 gene.

A novel missense mutation in the mediator of RNA polymerase II transcription subunit 12 (MED12) gene has been found in the original family with Lujan syndrome and in a second family (K9359) that was initially considered to have Opitz-Kaveggia (FG) syndrome. A different missense mutation in the MED12 gene has been reported previously in the original family with FG syndrome and in five other families with compatible clinical findings. Neither sequence alteration has been found in over 1400 control X chromosomes.

X-linked MCT8 gene mutations: characterization of the pediatric neurologic phenotype.

We report a family with X-linked mental retardation that has a novel mutation in the monocarboxylate transporter 8 (MCT8) gene associated with a characteristic neurodevelopmental phenotype with early childhood hypotonia that progresses to spasticity and global developmental delays. Affected patients experience moderate to severe psychomotor delays and congenital hypotonia, develop a myopathic facies, have diminished muscle bulk and generalized muscle weakness, develop progressive spasticity and movement disorders, and have limited speech but alert, affable personalities. Acquired microcephaly and abnormal myelination on brain magnetic resonance imaging can be present.

Allan-Herndon-Dudley syndrome and the monocarboxylate transporter 8 (MCT8) gene.

Allan-Herndon-Dudley syndrome was among the first of the X-linked mental retardation syndromes to be described (in 1944) and among the first to be regionally mapped on the X chromosome (in 1990). Six large families with the syndrome have been identified, and linkage studies have placed the gene locus in Xq13.2.