Prader-Willi syndrome (PWS) is a neurobehavioral disorder manifested by infantile hypotonia and feeding difficulties in infancy, followed by morbid obesity secondary to hyperphagia. It is caused by deficiency of paternally expressed transcript(s) within the human chromosome region 15q11.2. PWS patients harboring balanced chromosomal translocations with breakpoints within small nuclear ribonucleoprotein polypeptide N (SNRPN) have provided indirect evidence for a role for the imprinted C/D box containing small nucleolar RNA (snoRNA) genes encoded downstream of SNRPN. In addition, recently published data provide strong evidence in support of a role for the snoRNA SNORD116 cluster (HBII-85) in PWS etiology. In this study, we performed detailed phenotypic, cytogenetic, and molecular analyses including chromosome analysis, array comparative genomic hybridization (array CGH), expression studies, and single-nucleotide polymorphism (SNP) genotyping for parent-of-origin determination of the 15q11.2 microdeletion on an 11-year-old child expressing the major components of the PWS phenotype. This child had an B236.29 kb microdeletion at 15q11.2 within the larger Prader-Willi/Angelman syndrome critical region that included the SNORD116 cluster of snoRNAs. Analysis of SNP genotypes in proband and mother provided evidence in support of the deletion being on the paternal chromosome 15. This child also met most of the major PWS diagnostic criteria including infantile hypotonia, early-onset morbid obesity, and hypogonadism. Identification and characterization of this case provide unequivocal evidence for a critical role for the SNORD116 snoRNA molecules in PWS pathogenesis. Array CGH testing for genomic copy-number changes in cases with complex phenotypes is proving to be invaluable in detecting novel alterations and enabling better genotype-phenotype correlations. European Journal of Human Genetics (2010Genetics ( ) 18, 1196Genetics ( -1201 doi:10.1038/ejhg.2010; published online 30 June 2010Keywords: Prader-Willi syndrome; snoRNA; microdeletion; array CGH INTRODUCTION Prader-Willi syndrome (PWS; MIM 176270) is a neurobehavioral disorder caused by the lack of paternal expression of imprinted genes in the human chromosome region 15q11.2q13. PWS manifests as infantile hypotonia, genital hypoplasia, and neonatal feeding difficulties, followed by hyperphagia leading to profound obesity in early childhood and into adulthood. 1,2 Large interstitial deletions of B6-6.8 Mb at 15q11.2q13 of paternal origin are the cause in over 70% of cases. The majority of the remaining cases have maternal uniparental disomy (UPD) 15, and a small percentage have imprinting defects. Deletions at 15q11.2q13 of maternal origin result in Angelman syndrome (MIM 105830). Identification and characterization of the recurrent deletion breakpoints have revealed low-copy repeat-mediated nonallelic homologous recombination as the unifying mechanism for the common deletions and duplications across this interval. 3,4 A number of paternally expressed genes mapping with...

These findings provide further evidence that systemic primary carnitine deficiency presents with a broad clinical spectrum from a metabolic decompensation in infancy to an asymptomatic adult. The maternal systemic primary carnitine deficiency was uncovered by the newborn screening results supporting the previous notion that newborn screening can identify some of the maternal inborn errors of metabolism. It also emphasizes the importance of maternal evaluation after identification of a low free carnitine level in the newborn screening.

Fetal alcohol syndrome (FAS) is characterized by congenital anomalies traditionally associated with hearing disorders. The present study sought to (a) evaluate possible central hearing loss; (b) verify and extend previous observations on sensorineural and conductive hearing losses; (c) evaluate possible vestibular disorders; (d) examine the relationships between hearing, speech, language, vestibular, and dentofacial disorders in FAS patients; and (e) evaluate the influence of patient age, race, and gender on the expression of these morbidities. A biracial group of 22 FAS patients (aged 3 to 26 years) were evaluated by standard hearing, speech, language, and vestibular tests. Dentofacial and other malformations were also assessed. Of the 22 FAS patients, 17 (77%) had intermittent conductive hearing loss due to recurrent serous otitis media that persisted from early childhood into adulthood, whereas 6 (27%) had sensorineural hearing loss in addition to the conductive hearing loss. Among the 12 patients tested for central hearing function, all (100%) were significantly impaired. Among the patients tested for speech and language ability, 18 of 20 (90%) had speech pathology, 16 of 21 (76%) had expressive language deficits, and 18 of 22 (82%) had receptive language deficits. Hearing, speech, and language deficits were not influenced by age, race, or gender. On the vestibular tests, all performed within normal limits with the possible exception of one child (n = 6). High incidences of dentofacial, temporomandibular joint, ocular, cardiac, and skeletal disorders were observed. Race and gender tended to influence dental malocclusion class. Two subjects exhibited autistic tendencies. In conclusion, new and important findings included a high prevalence of sensorineural, conductive, and central hearing deficits, the persistence of otitis proneness into adulthood, the existence of temporomandibular joint disorders, and the possible influence of gender or race on dental malocclusions. Such disorders can contribute to the learning, behavioral, and emotional difficulties seen in FAS patients and warrant early, aggressive intervention.

Systemic primary carnitine deficiency (CDSP) is caused by recessive mutations in the SLC22A5 (OCTN2) gene encoding the plasmalemmal carnitine transporter and characterized by hypoketotic hypoglycemia, and skeletal and cardiac myopathy. The entire coding regions of the OCTN2 gene were sequenced in 143 unrelated subjects suspected of having CDSP. In 70 unrelated infants evaluated because of abnormal newborn screening (NBS) results, 48 were found to have at least 1 mutation/unclassified missense variant. Twenty-eight of 33 mothers whose infants had abnormal NBS results were found to carry at least 1 mutation/unclassified missense variant, including 11 asymptomatic mothers who had 2 mutations. Therefore, sequencing of the OCTN2 gene is recommended for infants with abnormal NBS results and for their mothers. Conversely, 52 unrelated subjects were tested due to clinical indications other than abnormal NBS and only 14 of them were found to have at least one mutation/unclassified variant. Custom designed oligonucleotide array CGH analysis revealed a heterozygous ~1.6 Mb deletion encompassing the entire OCTN2 gene in one subject who was apparently homozygous for the c.680G>A (p.R227H) mutation. Thus, copy number abnormalities at the OCTN2 locus should be considered if by sequencing, an apparently homozygous mutation or only one mutant allele is identified. ©2010 Wiley-Liss, Inc.

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