Hyperphosphatasia-mental retardation syndrome due to PIGV mutations: expanded clinical spectrum.

Hyperphosphatasia-mental retardation syndrome is a recently delineated disorder associated with a recognizable facial phenotype and brachytelephalangy. This autosomal recessive condition is caused by homozygous and compound heterozygous missense mutations of PIGV, encoding a member of the GPI-anchor biosynthesis pathway. Here, we report on two further, unrelated patients with developmental delay, elevated serum levels of AP, distinctive facial features, hypoplastic terminal phalanges, anal atresia in one and Hirschsprung disease in the other patient. By sequencing PIGV we detected compound heterozygous mutations c.467G>A and c.1022C>A in Patient 1 and a homozygous mutation c.1022C>A in Patient 2. We reviewed the eight reported cases with proven PIGV mutations and re-defined the phenotypic spectrum associated with PIGV mutations: intellectual disability, the distinct facial gestalt, brachytelephalangy, and hyperphosphatasia are constant features but also anorectal malformations and Hirschsprung disease as well as cleft lip/palate and hearing impairment should be considered as part of the clinical spectrum. Moreover, seizures and muscular hypotonia are frequently associated with PIGV mutations.

Clinical and mutational spectrum of Mowat-Wilson syndrome.

Mowat-Wilson Syndrome is a recently delineated mental retardation syndrome usually associated with multiple malformations and a recognizable facial phenotype caused by defects of the transcriptional repressor ZFHX1B. To address the question of clinical and mutational variability, we analysed a large number of patients with suspected Mowat-Wilson Syndrome (MWS). Without prior knowledge of their mutational status, 70 patients were classified into "typical MWS", "ambiguous" and "atypical" groups according to their facial phenotype. Using FISH, qPCR and sequencing, ZFHX1B deletions, splice site or truncating mutations were detected in all 28 patients classified as typical MWS. No ZFHX1B defect was apparent in the remaining 15 cases with ambiguous facial features or in the 27 atypical patients. Genotype-phenotype analysis confirmed that ZFHX1B deletions and stop mutations result in a recognizable facial dysmorphism with associated severe mental retardation and variable malformations such as Hirschsprung disease and congenital heart defects. Our findings indicate that structural eye anomalies such as microphthalmia should be considered as part of the MWS spectrum. We also show that agenesis of the corpus callosum and urogenital anomalies (especially hypospadias) are significant positive predictors of a ZFHX1B defect. Based on our observation of affected siblings and the number of MWS cases previously reported, we suggest a recurrence risk of around 1%. The lack of missense mutations in MWS and MWS-like patients suggests there may be other, as yet unrecognized phenotypes, associated with missense mutations of this transcription factor.

Mosaic and complete tetraploidy in live-born infants: two new patients and review of the literature.

Tetraploidy is a very rare finding in live-born infants. Nine infants with tetraploidy have been reported earlier. The phenotype is of variable severity and consists of prenatal and/or postnatal growth retardation, developmental delay, mental retardation, dysmorphic features, and skeletal and internal abnormalities. Here we present a girl aged 2 years and 7 months with a mosaic tetraploidy detected in lymphocytes, and a newborn boy with a complete tetraploidy, who died 30 h after birth. They both show growth retardation, microcephaly, developmental delay, and craniofacial dysmorphisms. The clinical features of 22 patients reported earlier are reviewed.