Prader-Willi syndrome

BACKGROUND: First described in 1956, Prader-Willi syndrome is a neurogenetic condition characterized by infantile hypotonia, hypogonadism and obesity. Mental deficiency, behavioral abnormalities, and obvious dysmorphic features are frequently found as well. It is a relatively common condition, with an incidence estimated to be between 1 in 10,000 to 25,000 live births. Few studies have been published that investigated the ocular defects associated with this syndrome. METHODS: This case report discusses the systemic and oculo-visual abnormalities of a 34-year-old white male enrolled in the Easter Seal Society of Metropolitan Chicago/Illinois College of Optometry Eye Care and Treatment Program. Examination techniques commonly used for patients with cognitive/developmental dysfunctions were utilized. RESULTS: Our findings include ocular hypopigmentation with reduced visual acuity, a myopic refractive error, exotropia, corneal abnormalities, glaucoma, and other ocular and systemic health abnormalities. CONCLUSIONS: Reported ocular findings for patients with Prader-Willi syndrome include iris hypopigmentation with depressed visual acuity, moderate to high refractive error, and strabismus. Individual patients with this syndrome have also been reported with cataracts, congenital ocular fibrosis syndrome, diabetic retinopathy, and congenital ectropion uveal. The numerous ocular, systemic, and functional abnormalities of patients with Prader-Willi syndrome make it mandatory that all routinely receive primary optometric vision care.     

Prader-Willi syndrome.

Although known for its distinctive food-related behaviors, Prader-Willi syndrome is a multisystem disorder with genetic, developmental, and behavioral features. Two separate and distinct eating disorders are noted: initial feeding difficulties and failure to thrive, and later overeating. Additional outcomes observed with this disorder include hypotonia, obesity, developmental/cognitive disabilities, and significant maladaptive behaviors. Symptoms vary in complexity across age and individuals. This necessitates multidisciplinary approaches to interventions across the life span to address medical, developmental, and behavioral issues. School psychologists have a vital role to play in assessment and consultation for individuals with this syndrome, their families, and school staff. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Laurence-Moon-Biedl syndrome (?) and Prader-Willi syndrome (?) in a single family

Mental retardation, hypogonadism, obesity, and abnormal blood sugar regulation were common findings in two siblings. In addition, the 17-year-old female patient showed short stature, muscular hypotonia in infancy, and small hands with tapering fingers suggesting Prader-Willi syndrome, and the 12-year-old male patient showed retinitis pigmentosa, normal height, and normal muscular tonicity suggesting Laurence-Moon-Biedl syndrome, though polydactyly was absent. Possible consideration was discussed.     

Diagnosis of Prader-Willi syndrome by reverse transcriptase polymerase chain reaction

To approve Prader-Willi syndrome by molecular diagnostic assay, polymerase chain reaction of reverse-transcribed RNA was introduced by which indirect information can be gained on all known forms of the mutation. In this pilot study, 4 patients and 16 healthy control individuals were examined. Although the different mutation forms can not directly by identified by this approach, it is a useful and reliable test to confirm the clinical diagnosis of the Prader-Willi syndrome, and to screen for the syndrome in patients who present with only a few typical features.     

Joubert syndrome: a report of 5 cases

OBJECTIVE: To review clinical features, radiological findings and prognosis in Joubert syndrome. MATERIAL AND METHODS: We report 5 children (3 male and 2 female) with the diagnosis of Joubert syndrome by clinical and radiological findings. They were diagnosed in the first year of life, in the Hospital Infantil La Paz (Madrid, Spain), from 1971 to 1996. Three patients have already been published, and here, we report two new cases. RESULTS: Partial absence of the cerebellar vermis, hypotonia and developmental delay were seen in all patients. Other cardinal findings were episodic hyperpnoea (5/5) with periods of apnoea (2/5), abnormal eye movements (2/5) and strabismus (3/5), tongue protrusion (2/5), seizures (1/5), hemifacial spasms (1/5) and occipital meningocele (2/5). Clinical manifestations were first noticed soon after birth. Two patients died in the first 5 years of life, and the rest of the cases actually show severe mental retardation. CONCLUSIONS: Joubert syndrome is a rare and probably underdiagnosed syndrome with bad prognosis. This inherited condition is characterized by agenesis of the cerebellar vermis, mental retardation, hypotonia, episodic hyperpnoea and abnormal eye movements. Additional manifestations have been reported since the original cases were described.     

Increased leptin messenger RNA and serum leptin levels in children with Prader-Willi syndrome and nonsyndromal obesity

To study the potential role of the ob gene pathway in childhood obesity, we have investigated leptin mRNA levels in s.c. adipose tissue obtained from nonobese prepubertal children (n = 20), obese nonsyndromal children (n = 6), and children with Prader-Willi syndrome (n = 6) by in situ hybridization histochemistry. We have also investigated the fasting serum leptin levels in such children. Compared with nonobese children, leptin mRNA expression was higher both in children with Prader-Willi syndrome and in children with nonsyndromal obesity (p < 0.01). Furthermore, the serum leptin levels were also significantly higher in both children with Prader-Willi syndrome and nonsyndromal obesity compared with the nonobese children (p < 0.001). However, no significant differences in adipose tissue leptin mRNA or serum leptin levels were observed between children with Prader-Willi syndrome and nonsyndromal obese children. As expected both fasting serum leptin levels and leptin mRNA expression levels correlated to body mass index (rs = 0.80 and 0.73, respectively, p < 0.005). No difference in leptin expression between Prader-Willi syndrome and nonsyndromal childhood obesity could be revealed in the present study. However, differences in the hypothalamic response to leptin between the two forms of obesity cannot be excluded.     

Receptor mechanism of the neuroprotective effect of GABAergic agents

Molecular genetic investigation of a female infant with Beckwith-Wiedemann syndrome (BWS) showed loss of IGF2 imprinting but no evidence of uniparental disomy. In addition, a deletion of chromosome 18q22.1 was identified in this infant without clinical features of 18q-syndrome (microcephaly, short stature, hypotonia). The association of a chromosome 18 deletion and BWS may be coincidental or may indicate the location of a trans activating regulator element for maintenance of IGF2 imprinting.     

A mild phenotype associated with der(9)t(3;9) (p25;p23)

A female infant is described with hypoglycaemia, hypotonia, obesity of the trunk and thighs, and mild dysmorphic features. Growth parameters were consistently above the 90th centile. Chromosome analysis showed her to have a derived chromosome 9 inherited from a maternal t(3;9)(p25;p23) by adjacent I segregation. She had features in common with both the dup(3p) and del(9p) syndromes. There are few reports of this chromosome rearrangement and the features are milder than expected for the degree of imbalance, complicated in males by sex reversal. The repeated reports of macrosomia may suggest an overgrowth syndrome.     

Evidence for uniparental, paternal expression of the human GABAA receptor subunit genes, using microcell-mediated chromosome transfer

We have constructed mouse A9 hybrids containing a single normal human chromosome 15, via microcell-mediated chromosome transfer. Cytogenetic and DNA-polymorphic analyses identified mouse A9 hybrids that contained either a paternal or maternal human chromosome 15. Paternal specific expression of the known imprinted genes SNRPN (small nuclear ribonucleoprotein-associated polypeptide N gene) and IPW (imprinted gene in the Prader-Willi syndrome region) was maintained in the A9 hybrids. Using this system, we first demonstrated that human GABAAreceptor subunit genes, GABRB3 , GABRA5 and GABRG3 , were expressed exclusively from the paternal allele and that E6-AP (E6-associated protein or UBE3A ) was biallelically expressed. Moreover, the 5' portion of the GABRB3 gene was found to be hypermethylated on the paternal allele. Our data imply that GABAAreceptor subunit genes are imprinted and are possible candidates for Prader-Willi syndrome, and that this human monochromosomal hybrid system enables the efficient analysis of imprinted loci.     

Assessment of preterm infants in the intensive-care unit to predict cerebral palsy and motor outcome at 6 years

One hundred and fifty-three infants were assessed by a method specific to preterm infants and appropriate to the intensive-care nursery environment. The presence or absence of six atypical features (coarse jitters, dominant asymmetrical tonic neck reflex, paucity of movement, 'contradictory' development, hypotonia, or hypertonia) resulted in neonatal classification. There were 116 'usual' (an absence of atypical features with progressive development), 26 'unusual' (a transient occurrence of any atypical feature), and 11 'suspect' (dominance of one or more atypical features). At 6 years of age the motor subsystems of balance, coordination, fine and gross motor, and associated movements were assessed. Nine of 11 children with cerebral palsy had neonatal categories of 'suspect' (7) and 'unusual' (2), of the remaining four other 'suspect' children, two failed two motor subsystems and two failed motor items. A 'usual' neonatal assessment predicted normal motor outcome for 72 of 116 (62%) whereas a 'suspect' assessment predicted major motor dysfunction for seven of 11 of the children.     

Fetal alcohol syndrome

The most notable features of fetal alcohol syndrome involve the face and eyes, and include microcephaly, short palpebral fissures, an underdeveloped philtrum and a thin upper lip. Evidence of intrauterine or postnatal growth retardation, mental retardation or other neurologic abnormalities, and at least two of the typical facial features are necessary to make the diagnosis. Newborns with the syndrome may be irritable, with hypotonia, severe tremors and withdrawal symptoms. Mild mental retardation, the most common and serious deficit, and a variety of other anomalies may accompany fetal alcohol syndrome. Sensory deficits include optic nerve hypoplasia, poor visual acuity, hearing loss, and receptive and expressive language delays. Atrial and ventricular septal defects, as well as renal hypoplasia, bladder diverticula and other genitourinary tract abnormalities, may occur. Complete abstinence during pregnancy is recommended, since alcohol consumption in each trimester has been associated with abnormalities, and the lowest innocuous dose of alcohol is not known.     

Treatment issues in genetic mental retardation syndromes.

Because of genetic advances and radical shifts in service delivery, psychologists in community mental health and social service agencies increasingly serve clients with mental retardation syndromes. Persons with specific genetic mental retardation syndromes often differ in their behavioral strengths and weaknesses and in their predispositions to psychiatric disorders. Although genetic breakthroughs are sparking more research on these so-called behavioral phenotypes, researchers have yet to systematically translate phenotypic data into guidelines for therapy and intervention. Using fragile X syndrome, Williams syndrome, and Prader-Willi syndrome as examples, this article shows how the behavioral phenotypes of mental retardation syndromes can inform clinical practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sj?gren''s syndrome associated with autoimmune hepatitis. A case report

We report on a 4-year-old girl with obesity and hyperphagia whose peripheral blood cytogenetic analysis showed mosaicism for a deletion of band 1p36.33. Terminal 1p deletions are rarely reported and this patient represents the first identified case of mosaicism. Given the subtlety of the cytogenetic abnormality and the possibility of mosaicism, the incidence of such deletions has probably been underestimated. While a characteristic phenotype associated with this karyotypic abnormality was described recently, the present report highlights the additional clinical findings of obesity and hyperphagia and the overlap of manifestations with Prader-Willi syndrome.     

Effects of hospital closure on mortality rates of the over-65 long-stay psychiatric population

We describe a girl with a brain-stem tumour and symptoms very similar to those of Rett syndrome (RS). Her early history was uneventful and development was normal (except for hypotonia). At the age of 6 months her development slowed. Subsequently, deterioration occurred and the features characteristic of RS were seen: loss of purposeful hand use, stereotypic hand movements, impaired social contact, decelerated head growth, and ataxia. Cerebral CT at the age of 3 years and 4 months revealed a tumour in the region of the pons and hydrocephalus. We suggest that a pons/midbrain tumour appearing at an early age may affect the developing CNS and cause symptoms similar to those of RS. A possible causal connection between midbrain pathology and RS is supported by this case.     

Hypotonia in infants and children

Many diseases in the pediatric population present with hypotonia and/or weakness. In order to ensure proper diagnosis and facilitate appropriate treatment, the nurse must be familial with those diseases which produce motor unit dysfunction in infants and children; among these conditions are infantile botulism and Guillain-Barré Syndrome. An understanding of the particular features which distinguish central from peripheral hypotonia is essential for the nurse. It is also important to obtain detailed histories and to ensure thorough physical examination. The nurse should also be aware of those laboratory studies that evaluate hypotonia and weakness, including the EMG, PNCT, muscle biopsy, and lumbar puncture.     

Clinical features and molecular genetic analysis of a boy with Prader-Willi syndrome caused by an imprinting defect

Prader-Willi syndrome (PWS) is a neuroendocrine disorder caused by a non-functioning paternally derived gene(s) within the chromosome region 15q11-q13. Most cases result from microscopically visible deletions of paternal origin, or maternal uniparental disomy of chromosome 15. In both instances no recurrence has been reported. In rare cases, PWS is associated with lack of gene expression from the paternal allele due to an imprinting defect. We report the clinical features and the molecular genetic analysis of the first Danish child with PWS due to a defect of the putative imprinting centre (IC). When the imprinting mutation is inherited from a carrier father, the risk that future children will be affected is theoretically 50%. It is therefore important that these families are referred to a geneticist for counselling and further investigation. Prenatal diagnosis is currently only feasible when the mutation has been identified in the affected child.     

Cowden's disease with a defined genetic alteration--chromosomal duplication at 15q11-q13

Cowden's disease, multiple hamartoma syndrome, is a dominantly inherited disorder characterized by multiple hamartomas of ectodermal, endodermal, and mesodermal origin and also by a high incidence of malignant tumors. Despite many efforts to identify the genetic alterations responsible for the syndrome, the molecular mechanism remains unclear. We report a case of Cowden's disease in which karyotype analysis revealed a small duplication (about 1 Mb) at 15q11-q13. This part of the genome is a region that is deleted in the Prader-Willi/Angelman syndrome and is a "hot spot" of chromosomal duplication.