Clinical and genetic heterogeneity in chromosome 9p associated hereditary inclusion body myopathy: exclusion of GNE and three other candidate genes

We have previously reported a new autosomal dominant inclusion body myopathy clinically resembling limb girdle muscular dystrophy, associated with Paget disease of bone in the majority and frontotemporal dementia in a third of individuals. The critical locus for this unique disorder now termed IBMPFD is 9 p21.1-p12, spans 5.5 Mb and contains the gene responsible for the recessive quadriceps-sparing inclusion body myopathy (IBM2). Mutation analysis of the GNE gene associated with IBM2 in affected individuals from four IBMPFD families did not identify any mutations, indicating that the two disorders are not allelic. Expression studies indicate that GNE has a tissue-specific splice pattern, with four splice variants. Mutation analysis in three other candidate genes (beta-tropomyosin, NDUFB6 and SMU1) did not identify any mutations.     

Heterotopic perineal intestinal mucosa —a variant of the exstrophy-epispadias complex

We report two cases of sequestration of a segment of intestinal mucosa in the perineal area. In one patient this was associated with a mildly ectopic anus. No abnormalities were identified in the bladder, urethra, vagina, or rectum. The lesions were treated by excision following complete anatomical mapping.     

Comparison of perinatal factors in deletion versus uniparental disomy in Prader–Willi syndrome

Prader–Willi syndrome (PWS) is caused by a deficiency of imprinted genes in the 15q11‐q13 region and is characterized by prenatal onset of hypotonia, poor feeding, childhood‐onset obesity, hyperphagia, short stature, facial dysmorphism, intellectual disability, and behavioral problems. We studied perinatal factors in a cohort of 64 people with PWS resulting from paternal deletion of 15q11‐q13 and maternal uniparental disomy (UPD) for chromosome 15. We recruited 34 individuals with deletion and 30 with UPD. We compared the frequency of multiple prenatal and neonatal factors with the general population as well as between the two genetic subtypes. Of the 64 individuals with PWS, fetal movements were decreased in 82.8%, 31.7% were born prematurely, 42.1% by Cesarean section, and 35.9% required oxytocin induction. Apgar scores were low in 34.6%, 96.8% had feeding difficulty, 50% needed tube feeding, and 6.2% subsequently had gastrostomy tube placement. On comparing findings in the deletion versus the UPD groups, we did not find many significant differences. We, however, found a higher maternal age, and also later age at diagnosis in the UPD versus the deletion group. PWS subjects have higher rates of perinatal complications, especially Cesarean section rate, hypotonia, and low Apgar scores compared to the general population. We did not find many differences between the genetic subtypes, except for later age of diagnosis of the UPD 15 group suggesting a milder phenotype. We also found that the mothers in the UPD were older, supporting the hypothesis that UPD results from nondisjunction associated trisomy rescue.     

Possible new autosomal recessive syndrome of partial agenesis of the corpus callosum,pontine hypoplasia,focal white matter changes,hypotonia, mental retardation,and minor anomalies

We describe a brother and sister with severe developmental delay, hypotonia, partial agenesis of the corpus callosum, pontine hypoplasia, focal white matter degenerative abnormalities, macrocrania, frontal bossing, deep-set eyes, and hypertelorism. The brother also had Duane syndrome type II and an ectopic right ureter. The coexistence of these multiple physical and brain abnormalities in a brother and sister suggests a new autosomal recessive syndrome with a slowly progressive course. Am. J. Med. Genet. 73:184–188, 1997. © 1997 Wiley-Liss, Inc.     

Genetics of hearing loss: where are we standing now?

Hearing loss (HL) is the most common sensory impairment and is caused by a broad range of inherited to environmental causes. Inherited HL consists 50–60% of all HL cases. The inherited form of HL is further classified to different categories. More than 300 syndromes and 40 genes have been identified to result in different levels of HL. Although several diagnostic or screening tests have been developed, yet there are controversies around their use.