13 novel putative mutations in ATP7A found in a cohort of 25 Italian families.

ATP7A is a copper-transporting P-type adenosine triphosphatase whose loss of function leads to the Menkes disease, an X-linked copper metabolism multi-organ disorder (1 in 100.000 births). Here we document our experience with the ATP7A linked diseases in Italy. We analyzed the exonic structure of the ATP7A gene in 25 unrelated Italian families and studied the variants of unknown significance. We identified 22 different DNA alterations, 13 of which first reported in this study. The classical Menkes phenotype was present in 21 of the 25 families and was linked with highly damaging mutations (7 nonsense; 4 frame-shift; 2 small in-frame deletions, 2 splice site alterations, 2 gross deletions, and 1 gross duplication). Of the 4 cases with milder variants of the Menkes disease two had a missense mutation, one a leaky splice site alteration and one a nonsense mutation in exon 22. We determined in silico that all the mutations leading to the classical Menkes disease leave no residual activity of ATP7A including the apparently less severe in-frame deletions. Whereas milder forms of the disease are characterized by mutations that allow a limited residual activity of ATP7A, including the nonsense mutation observed.

Analysis of the HPRT1 gene in 35 Italian Lesch-Nyhan families: 45 patients and 77 potential female carriers.

BACKGROUND: Lesch-Nyhan (LND) disease is an inborn error of purine metabolism which results from deficiency of the activity of hypoxanthine-guanine phosphoribosyltransferase (HPRT). In the classical form of the disease the activity of the enzyme is completely deficient and the patient has cognitive impairment, spasticity, dystonia and self-injurious behaviour, as well as elevated concentrations of uric acid in blood and urine that leads to consequences such as nephropathy, urinary tract calculi and tophaceous gout. There are disease variants without self-injurious behaviour. In these cases neurological manifestations may vary widely. The HPRT1 gene is located on the X chromosome in position Xq26-27.2, and mutations have been found in quite a large number of patients. OBJECTIVE: Documenting our experience with the diagnosis of LND in 45 Italian patients from 35 nonrelated families and 77 females at risk of being carriers of the condition. DESIGN: Internal review. SETTING: An institute devoted to the investigation and care of patients with rare diseases. RESULTS: In 94% of the LND families gDNA sequencing of the patients was informative while in 6% a cDNA study was required. For the carrier females gDNA sequencing was informative in 71% of the families, 23% required qPCR studies and 6% required segregation studies combined with enzymatic activity testing. Classical cDNA studies proved to be unreliable in carrier females as there is a significant risk of failure to detect the mutated allele. Four novel HPRT1 mutations were found: c.145C>T (p.Leu49Phe), c.112C>T (p.Pro38Ser), c.89_96dup8 (p.Glu33Argfs) and c.506dupC (p.Arg170Thrfs). CONCLUSION: In the diagnosis of LND it is very important to consider all the possible alterations of the HPRT1 gene when searching for mutations especially if no affected male is available. Biochemical assessment of the enzymatic activity of HPRT in an affected male is the ideal starting point for molecular analysis of the gene.

Clinical and Molecular Characterization of Prader-Willi Syndrome.

OBJECTIVES: To describe the clinical presentations and molecular diagnosis to aid the clinicians in early diagnosis and appropriate management of Prader-Willi syndrome (PWS). METHODS: Thirty-four clinically diagnosed PWS cases were enrolled after obtaining informed consent/assent. Demographic details, clinical data and anthropometry were recorded using structured proforma. The facial dysmorphology was evaluated. Appropriate genetic testing was performed to confirm the diagnosis. RESULTS: At diagnosis, the most common clinical features included obesity (59%) and short stature (53%). Distinct dysmorphic features were observed in 67%. Neonatal hypotonia with feeding difficulty, delayed development in infancy and childhood behavioral problems were reported in 94%, 94% and 74% respectively. Food seeking behavior and hyperphagia was reported in 67%. Seizures were reported in 47%. All children had underdeveloped external genitalia. Growth hormone (GH) deficiency and impaired glucose tolerance were found in 56% and 50% respectively. Sleep related problems were seen in 67%. Skin and rectal picking were reported in 67%. FISH confirmed micro-deletion was found in 64.7% and abnormal methylation in 35%, of which uniparental disomy was confirmed in 14.7%. CONCLUSIONS: Clinical suspicion is vital for early detection of PWS. Confirmation of the diagnosis requires complex multi-tier molecular genetic testing.