Carbohydrate-deficient glycoprotein syndrome type 1 (CDG1) is an autosomal recessive, metabolic disorder with severe psychomotor retardation and a high mortality rate in early childhood.
We determined the DNA sequence of the adenylosuccinate lyase (ASL) gene from a 13 year-old female, who showed a reduced ASL enzymatic activity in lymphocytes and red blood cells and suffered from severe psychomotor retardation.
A four-year-old boy with severe psychomotor retardation, facial appearance consistent with the fragile X syndrome, hypotonia, and overgrowth was found to have a deletion including the fragile X gene (FMR1).
Congenital microcephaly, intractable seizures and severe psychomotor retardation characterize 3-phosphoglycerate dehydrogenase (3-PGDH) deficiency, a disorder of L-serine biosynthesis.
We tested whether mutations in MCT8 cause severe psychomotor retardation and high serum triiodothyronine (T3) concentrations in five unrelated young boys.
These findings support the hypothesis that the severe psychomotor retardation and elevated serum T(3) levels in these patients are caused by inactivation of the MCT8 transporter, preventing action and metabolism of T(3) in central neurons.
Mutational analysis of the MCT8 gene revealed mutations or deletions in the MCT8 gene in unrelated male patients with severe psychomotor retardation and biochemical findings consistent with thyroid hormone resistance.
Mutations of the monocarboxylate transporter 8 (MCT8) gene determine a distinct X-linked phenotype of severe psychomotor retardation and consistently elevated T(3) levels.
Mutations in MCT8 are associated with elevated serum T(3) levels and severe psychomotor retardation, indicating a pivotal role for MCT8 in brain development.
The pathophysiological importance of thyroid hormone transporters has been established by the demonstration of MCT8 mutations in patients with severe psychomotor retardation and elevated serum T(3) levels.
Haploinsufficiency of NTNG1, LPPR4, GPSM2, COL11A1 and VAV3 might have contributed to the severe psychomotor retardation and unusual craniofacial features in this patient.
Our review of previously reported cases with TCF4 mutations and deletions showed that all patients with Pitt-Hopkins syndrome reported to date have severe psychomotor retardation, the onsets of seizures and hyperventilation episodes are limited to the first decade in most reported patients with Pitt-Hopkins syndrome, hyperventilation episodes are more common than seizures and are seen in the oldest patients, and individuals with missense TCF4 mutations are more likely to develop seizures.
In case 1, CMA revealed an approximately 140 kb deletion encompassing the first three exons of MEF2C in a 3-year-old patient with severe psychomotor retardation, periodic tremor, and an abnormal motor pattern with mirror movement of the upper limbs observed during infancy, hypotonia, abnormal EEG, epilepsy, absence of speech, autistic behavior, bruxism, and mild dysmorphic features.
Mutations in the MCT8 gene are associated with Allan-Herndon-Dudley Syndrome (AHDS), consisting of severe psychomotor retardation and disturbed TH parameters.
Hemizygous MCT8 mutations in males cause severe psychomotor retardation, known as the Allan-Herndon-Dudley syndrome (AHDS), and abnormal serum TH levels.
Mutations in MCT8 are associated with the Allan-Herndon-Dudley syndrome (AHDS), characterized by severe psychomotor retardation and altered serum thyroid parameters.
By way of whole-exome sequencing, we identified a homozygous missense mutation in VARS2 in one subject with microcephaly and epilepsy associated with isolated deficiency of the mitochondrial respiratory chain (MRC) complex I and compound heterozygous mutations in TARS2 in two siblings presenting with axial hypotonia and severe psychomotor delay associated with multiple MRC defects.
By way of whole-exome sequencing, we identified a homozygous missense mutation in VARS2 in one subject with microcephaly and epilepsy associated with isolated deficiency of the mitochondrial respiratory chain (MRC) complex I and compound heterozygous mutations in TARS2 in two siblings presenting with axial hypotonia and severe psychomotor delay associated with multiple MRC defects.