A novel AXIN2 gene mutation in sagittal synostosis.

The bones of the skull are held together by fibrous joints called sutures. Premature fusion of these sutures leads to a pathologic condition called as craniosynostosis. Although at least 50 nuclear genes including FGFR2, TWIST1, TCF12, and SMAD6 were identified as causative of craniosynostosis; only 25% of the patients can be genetically diagnosed. Here, we report a 3-year-old Turkish Caucasian boy with sagittal craniosynostosis with a de novo loss-of-function mutation in exon 4 of the AXIN2 gene for the first time. The patient has frontal bossing, high anterior hair line, depressed nasal bridge, bilateral epicanthus and low set ears which are correlated with his scaphocephaly. As a negative regulator of the Wnt signaling pathway which is one of the key modulators of craniosynostosis syndrome, it has been shown in model organisms that Axin2 orchestrates the regulation of beta-catenin especially in the intramembranous ossification process. This clinical report adds value to the literature that AXIN2 gene mutations could be a potential cause in human calvarial malformations, especially for the sagittal synostosis.

Pyridoxine-Responsive Seizures in Infantile Hypophosphatasia and a Novel Homozygous Mutation in ALPL Gene.

Hypophosphatasia is a rare inherited disorder of bone and mineral metabolism caused by a number of loss-of-function mutations in the ALPL gene. It is characterized by defective bone and tooth mineralisation associated with low serum and bone alkaline phosphatase activity. The clinical presentation of this disease is extremely variable. For this reason, the diagnosis can be difficult and is often missed out or delayed. Hypophosphatasia is classified into subtypes based on the age of onset and clinical features. The clinical severity is associated with the age at diagnosis and the lack of tissue-nonspecific alkaline phosphatase activity; the severe forms of hypophosphatasia are primarily perinatal and infantile forms. Severe forms may present with many neurological problems such as seizures, hypotonia, irritability. Herein, we report the case of an infantile hypophosphatasia patient who presented with pyridoxine-responsive seizures and a novel homozygous mutation in the ALPL gene was detected. There is a limited number of hypophosphatasia patients with pyridoxine-responsive seizures in the literature, so early diagnosis of infantile hypophosphatasia in the clinically compatible patients allows more effective postnatal care/management and genetic counseling for further pregnancies.