in india , the prevalence of inborn errors of metabolism is one in 2497 newborns and alkaptonuria have incidence of about 1/250 , 000 .
a delay in diagnosis and treatment of this disease can result in arthritis and ochronosis ( darkening of the tissues ) due to the slow accumulation of the dark polymer of homogentisic acid ( ha ) in cartilage and other mesenchymal tissue ; this leads to the dark blackened spots in the sclera , cornea , ear cartilage , and arthritis with advancing age .
one was a 4-month - old female baby born of a non - consanguineous marriage and another early presentation was reported at the age of 10 years with the complaint of bluish discoloration of sclera .
our case was a 1-year 5-month - old male child , brought with complaints of reddish discoloration of the nappies and clothes and breath - holding spells .
there was no history of crying while passing urine , poor urinary stream or bleeding from skin or mucus membrane .
there was no history of fever , rash , abdominal pain , constipation or alteration of sensorium .
the mother of the baby was a known case of thalassemia trait ; however , had never received transfusion . the baby s parents were consanguineous cousins . the father s thalassemia status could not be elicited . on examination ,
the baby weighed 8.5 kg with head circumference 44 cm and length 81 cm and the baby was conscious and alert .
the capillary refill time was between 3 s and 4 s. the heart rate was 146/min .
the baby was admitted for observation and investigations , and the initial differential diagnosis included alkaptonuria , myoglobinuria , hemoglobinuria , porphyria , and hemochromatosis .
hemoglobin was 10.2 g / dl ( normal 10.5 - 14 g / dl ) , packed cell volume , mean corpuscular volume ( mcv ) and mean corpuscular hemoglobin were low at 31.9% ( normal 32 - 42% ) , 68 fl ( normal 72 - 88 fl ) , and 21.8 pg ( normal 24 - 30 pg ) , respectively .
mcv concentration was 32% ( normal 31.5 - 34.5% ) and red cell distribution width 17.1% ( normal 11 - 16% ) .
serum iron , total iron binding capacity , and ferritin levels were within the reference range .
hemoglobin analysis by cation exchange high - pressure liquid chromatography ( hplc ) revealed hb a0 to be 80.4% and hb a2 to be 6.1% ( normal 2.40 - 3.60 ) . the hplc picture on correlation with the complete hemogram suggested -thalassemia trait .
the renal function and liver function were within the reference range . the child s urine porphyrin , estimations were within normal levels , and serum lead levels and -amino levulinic acid were not tested .
no abnormalities were detected on the electroencephalogram , leading us to believe that the breath holding spells were due to anemia .
urine was of normal color when voided but turned black over variable periods spontaneously ; furthermore , turned black with benedict s reagent , strong alkali ( filter paper impregnated with 10% sodium hydroxide turned black within 5 min when dipped into the urine ) and ferric chloride ( addition of dilute ferric chloride solution drop by drop showed an evanescent violet blue color ) .
however , it starts to darken upon standing , and this is caused by oxidation and polymerization of the homogentisic acid , and it is enhanced with an alkaline ph .
benedict s test was strongly positive with red brown precipitate at the bottom and black colored supernatant .
glucose oxidase test ( with multistix ) was negative excluding the role of glucose as reducing substance .
for the qualitative assay of ha , to 0.5 ml of sample , a few drops of 10% ammonia was added followed by the addition of 3% silver nitrate solution .
a greenish black color developed , signifying the presence of a substantial amount of ha . quantitative examination of urine by tandem mass spectrometry revealed that concentration of ha in urine was 91 mg / dl ( normally ha is not present in urine ) .
the child was treated symptomatically , and he was given vitamin c ( 50 mg once a day for 3 months ) , low phenylalanine and tyrosine diet , and advised to monitor counts , get liver and renal function tests carried out every 2 weeks .
on the request of his parents , the child was discharged after 3 days and advised to follow - up in the outpatient department ( opd ) .
after 3 months post - therapy , his ha levels had not reduced . currently , the baby is under follow - up every 6 months in the opd .
alkaptonuria is due to an inborn error of metabolism of the tyrosine linkage in the process of protein metabolism , the end product being 1 , 4-dihydroxyphenyl - acetic ( homogentisic ) acids , which is passed into the urine .
alkapton urine is normal in color when freshly passed , but on exposure to air and light rapidly darkens from the surface downwards , ultimately assuming a dark - brown or black color .
therefore , its presence can be detected in urine quite readily by first making the urine strongly alkaline with caustic soda or caustic potash .
this color change does not take place with the substances occurring normally in urine , or pathologically except with homogentisic acid .
isolated case reports from india are also available . however , our case is probably the first documented case of alkaptonuria co - existing with thalassemia in a 1-year 5-month old baby with no symptom except reddish discoloration of nappies and clothes .
our use of basic biochemical tests supported the heightened index of suspicion to lead us to a diagnosis in 3 days .
the gene encoding homogentisate 1 , 2-dioxygenase , is the only gene in which mutations are known to cause alkaptonuria .
various presentations of alkaptonuric patients have been described such as aortic valve regurgitation and inferior myocardial infarction , ochronosis with joint pain , end - stage renal failure and pigmented conjunctival lesions .
the aminoacids tyrosine and phenylalanine are not metabolized beyond the stage of homogentisic acid , which is , therefore , excreted in urine .
ha is a strong reducing agent , which on exposure to atmospheric oxygen for some hours , gets converted to an oxidized polymer that is black in color .
levels of ha in the blood are minimally increased because it is rapidly cleared by the kidneys . since
, ascorbic acid impedes oxidation and polymerization of ha in vitro , its use has been suggested as a possible means of decreasing pigment formation and deposition .
estimates show that 1.5% of world populations are carriers of -thalassemia , and about 50% of incidence is from south - east asian population , which mainly includes countries such as india , thailand , and indonesia .
the carrier rate for -thalassemia varies from 1% to 17% in india with an average of 3.2% . curtin and kan
although , co - incidence of more than one inherited disease in highly consanguineous kinships has been described , the novel combination of alkaptonuria and -thalassemia has not yet been reported in the literature .
further , genetic studies are required to analyze any possible linkage between thalassemia and alkaptonuria .
we would however like to stress that in infancy , a history of dark - stained diapers should alert the physician to alkaptonuria , and they can be evaluated with simple urine testing on an outpatient basis .
a mild dietary restriction of phenylalanine and tyrosine reduces ha excretion , thus , avoiding or minimizing later complications .
the mild antioxidant nature of ascorbic acid helps to retard the process of conversion of homogentisate to the polymeric material that is deposited in cartilaginous tissues .
although limited use of nitisinone , an inhibitor of the enzyme 4-hydroxyphenylpyruvate dioxygenase , which mediates the formation of ha , has been reported , safety of prolonged use is still an open question .
 since the aggregate incidence of inborn errors of metabolism is relatively high , a high degree of suspicion is essential to correctly diagnose an inborn error of amino acid metabolism . 
 we report a case of alkaptonuria an autosomal recessive disorder that occurs due to deficiency of homogentisic acid oxidasein a -thalassemia infant presenting with reddish discoloration of nappies and clothes , breath holding spells , and microcytic hypochromic anemia . born to consanguineous cousins , to our knowledge , the combination of -thalassemia and alkaptonuria , which we have described in this baby , has not been reported earlier . 
Introduction
Case Report
Discussion