Dysregulation of erythropoiesis and altered erythroblastic NMDA receptor-mediated calcium influx in Lrfn2-deficient mice.

LRFN2 encodes a synaptic adhesion-like molecule that physically interacts with N-methyl-D-aspartate (NMDA) receptor 1 and its scaffold proteins. Previous studies in humans and mice have demonstrated its genetic association with neurodevelopmental disorders such as learning deficiency and autism. In this study, we showed that Lrfn2-deficient (KO) mice exhibit abnormalities of erythropoietic systems due to altered NMDA receptor function. In mature Lrfn2 KO male mice, peripheral blood tests showed multilineage abnormalities, including normocytic erythrocythemia, and reduced platelet volume. Colony forming unit assay using bone marrow cells revealed decreases in the counts of erythrocyte progenitors (CFU-E) as well as granulocytes and monocyte progenitors (CFU-GM). Whole bone marrow cell staining showed that serum erythropoietin (EPO) level was decreased and EPO receptor-like immunoreactivity was increased. Flow cytometry analysis of bone marrow cells revealed increased early erythroblast count and increased transferrin receptor expression in late erythroblasts. Further, we found that late erythroblasts in Lrfn2 KO exhibited defective NMDA receptor-mediated calcium influx, which was inhibited by the NMDA receptor antagonist MK801. These results indicate that Lrfn2 has biphasic roles in hematopoiesis and is associated with the functional integrity of NMDA receptors in hematopoietic cells. Furthermore, taken together with previous studies that showed the involvement of NMDA receptors in hematopoiesis, the results of this study indicate that Lrfn2 may regulate erythropoiesis through its regulatory activity on NMDA receptors.

EEC-LM-ADULT syndrome caused by R319H mutation in TP63 with ectrodactyly, syndactyly, and teeth anomaly: A case report.

RATIONALE: Ectrodactyly ectodermal dysplasia-cleft lip/palate (EEC) syndrome, limb-mammary syndrome (LMS), and acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome are caused by a TP63 gene disorder and have similar features. In the present article, a R319H mutation in TP63 is reported, and the correlation between genotype and phenotype is discussed based on the current case and previous literature. PATIENT CONCERNS: A 13-year-old Japanese boy had ectrodactyly in the right hand and left foot and syndactyly in the left and right foot, and tooth shape abnormalities. DIAGNOSES: Peripheral blood samples were obtained, and mutation analysis was performed. A heterozygous G>A transition at cDNA position 956 of the TP63 gene was found. The patient was diagnosed with ELA (EEC/LM/ADULT) syndrome based on his clinical features and mutation analysis results. INTERVENTIONS: The patient underwent surgery to correct the left foot malformation at 1 year of age and the right foot syndactyly at 11 years of age. OUTCOMES: No complications were observed after the first and second operations. He can walk comfortably after them, and no additional interventions will be planned in him. We continued to follow up with him up to the present. LESSONS: The concept of ELA syndrome, which is the original concept of combining 3 syndromes (EEC syndrome/LMS/ADULT syndrome) into a unique clinical entity, can help clinicians to better understand TP63-related syndromes and improve the differential diagnosis of these syndromes.

Three brothers with a nonsense mutation in KAT6A caused by parental germline mosaicism.

Mutations in KAT6A, encoding a member of the MYST family of histone acetyl-transferases, were recently reported in patients with a neurodevelopmental disorder (OMIM: #616268, autosomal dominant mental retardation-32). In this report, we describe three siblings with intellectual disability (ID) or global developmental delay and a KAT6A heterozygous nonsense mutation, i.e., c.3070C>T (p.R1024*, ENST00000406337; chr8:41795056G>A on hg19). This mutation was identified by whole-exome sequencing of all three siblings but not in a healthy sibling. The mutation was not detected in the peripheral blood of their parents, suggesting the existence of parental germline mosaicism. The primary symptoms of our patients included severe to profound ID or global developmental delay, including speech delay with craniofacial dysmorphism; these symptoms are consistent with symptoms previously described for patients with KAT6A mutations. Although several features are common among patients with KAT6A mutations, the features are relatively nonspecific, making it difficult to establish a clinical entity based on clinical findings alone. To the best of our knowledge, this is the first report of cases with a KAT6A mutation in an Asian population and these cases represent the first reported instances of germline mosaicism of this disease.

Intermediate Phenotype between ADULT Syndrome and EEC Syndrome Caused by R243Q Mutation in TP63.

A patient who had ectrodactyly, dry skin, exfoliative dermatitis, and hypodontia with peg-shaped teeth, but not cleft lip and palate, is described. Ectrodactyly with a tooth anomaly is recognized in both acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome and ectrodactyly-ectodermal dysplasia-cleft (EEC) syndrome. These 2 syndromes are caused by heterozygous mutations in the transcriptional factor gene p63. Mutation analysis of p63 gene showed a heterozygous mutation c.728G>A, p.Arg243Gln (previously referred to as R204Q) in the patient, but not in his parents. Therefore, this was a sporadic case of the p63 mutation-associated disorder. Although the mutation has been mostly reported in EEC syndrome patients, the present case did not have cleft lip and palate. Furthermore, the present case did not exhibit freckling or some of the other ectodermal dysplasia phenotypes typical of ADULT syndrome. The concept of ELA syndrome proposed by Prontera in 2011 resolves the problem confronted in diagnosing the present case. ELA syndrome is an acronym of EEC/limb-mammary syndrome/ADULT syndromes, and these 3 syndromes are united into a unique entity. This system can classify p63 mutation-associated disorders simply without interfering with treatment.