RESUMEN
PPFIBP1 encodes for the liprin-ß1 protein, which has been shown to play a role in neuronal outgrowth and synapse formation in Drosophila melanogaster. By exome and genome sequencing, we detected nine ultra-rare homozygous loss-of-function variants in 16 individuals from 12 unrelated families. The individuals presented with moderate to profound developmental delay, often refractory early-onset epilepsy, and progressive microcephaly. Further common clinical findings included muscular hyper- and hypotonia, spasticity, failure to thrive and short stature, feeding difficulties, impaired vision, and congenital heart defects. Neuroimaging revealed abnormalities of brain morphology with leukoencephalopathy, ventriculomegaly, cortical abnormalities, and intracranial periventricular calcifications as major features. In a fetus with intracranial calcifications, we identified a rare homozygous missense variant that by structural analysis was predicted to disturb the topology of the SAM domain region that is essential for protein-protein interaction. For further insight into the effects of PPFIBP1 loss of function, we performed automated behavioral phenotyping of a Caenorhabditis elegans PPFIBP1/hlb-1 knockout model, which revealed defects in spontaneous and light-induced behavior and confirmed resistance to the acetylcholinesterase inhibitor aldicarb, suggesting a defect in the neuronal presynaptic zone. In conclusion, we establish bi-allelic loss-of-function variants in PPFIBP1 as a cause of an autosomal recessive severe neurodevelopmental disorder with early-onset epilepsy, microcephaly, and periventricular calcifications.
Asunto(s)
Epilepsia , Microcefalia , Malformaciones del Sistema Nervioso , Trastornos del Neurodesarrollo , Acetilcolinesterasa/genética , Animales , Drosophila melanogaster/genética , Epilepsia/genética , Pérdida de Heterocigocidad , Microcefalia/genética , Trastornos del Neurodesarrollo/genética , LinajeRESUMEN
The dpy-19 like 2 (DPY19L2) gene is the most common genetic cause of globozoospermia characterised by the production of round-headed spermatozoa without an acrosome. The present study was performed on 63 men with globozoospermia and 41 normozoospermic individuals to evaluate the frequency of the DPY19L2 gene and exons; deletion and genetic changes in exons 1, 5, 7-11, 19, 21 and interval introns; and some epidemiological factors (e.g. varicocele, smoking, drug use, alcohol consumption and a family history of infertility). Homozygous deletion of DPY19L2 was identified in 35% of men with globozoospermia. Exon 7 was deleted in 4.8% of men with globozoospermia in which DPY19L2 was not deleted. No genetic variations were observed within the DPY19L2 exons examined, but five intronic polymorphisms were detected: 1054-77T>C in intron 9, 1131+65T>C and 1131+53A>G in intron 10 and 1218+22T>C and 1218+73T>C in intron 11. There were significant differences in the frequency of 1054-77T>C and 1218+22T>C polymorphisms between the globozoospermic and normozoospermic groups. In addition, there were significant differences between the two groups in sperm count, sperm motility, a history of infertility in the family and varicocele. Based on these findings, DPY19L2 deletion is the major cause of total globozoospermia and there is no association between exons 1, 5, 8-11, 19 and 21 polymorphisms of the DPY19L2 gene in the occurrence of this defect.
Asunto(s)
Eliminación de Gen , Infertilidad Masculina/genética , Proteínas de la Membrana/genética , Teratozoospermia/genética , Exones/genética , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Variación Genética/genética , Homocigoto , Humanos , Irán/epidemiología , Masculino , Polimorfismo Genético/genética , Análisis de Secuencia de ADN , Recuento de Espermatozoides , Motilidad Espermática , Teratozoospermia/epidemiología , Varicocele/epidemiologíaRESUMEN
The dpy-19 like 2 (DPY19L2) gene is the most common genetic cause of globozoospermia characterised by the production of round-headed spermatozoa without an acrosome. The present study was performed on 63 men with globozoospermia and 41 normozoospermic individuals to evaluate the frequency of the DPY19L2 gene and exons; deletion and genetic changes in exons 1, 5, 7-11, 19, 21 and interval introns; and some epidemiological factors (e.g. varicocele, smoking, drug use, alcohol consumption and a family history of infertility). Homozygous deletion of DPY19L2 was identified in 35% of men with globozoospermia. Exon 7 was deleted in 4.8% of men with globozoospermia in which DPY19L2 was not deleted. No genetic variations were observed within the DPY19L2 exons examined, but five intronic polymorphisms were detected: 1054-77T>C in intron 9, 1131+65T>C and 1131+53A>G in intron 10 and 1218+22T>C and 1218+73T>C in intron 11. There were significant differences in the frequency of 1054-77T>C and 1218+22T>C polymorphisms between the globozoospermic and normozoospermic groups. In addition, there were significant differences between the two groups in sperm count, sperm motility, a history of infertility in the family and varicocele. Based on these findings, DPY19L2 deletion is the major cause of total globozoospermia and there is no association between exons 1, 5, 8-11, 19 and 21 polymorphisms of the DPY19L2 gene in the occurrence of this defect.